diff --git a/Documentation/config-gerrit.txt b/Documentation/config-gerrit.txt
index 93d2a52..f0a22cd 100644
--- a/Documentation/config-gerrit.txt
+++ b/Documentation/config-gerrit.txt
@@ -3094,7 +3094,7 @@
 [[index.batchThreads]]index.batchThreads::
 +
 Number of threads to use for indexing in background operations, such as
-online schema upgrades, and also for offline reindexing.
+online schema upgrades, and also the default for offline reindexing.
 +
 If not set or set to a zero, defaults to the number of logical CPUs as returned
 by the JVM. If set to a negative value, defaults to a direct executor.
@@ -3297,6 +3297,11 @@
 +
 Defaults to true (throttling enabled).
 
+During offline reindexing, setting ramBufferSize greater than the size
+of index (size of specific index folder under <site_dir>/index) and
+maxBufferedDocs as -1 avoids unnecessary flushes and triggers only a
+single flush at the end of the process.
+
 Sample Lucene index configuration:
 ----
 [index]
diff --git a/Documentation/dev-plugins.txt b/Documentation/dev-plugins.txt
index aae37b5..67e49eb 100644
--- a/Documentation/dev-plugins.txt
+++ b/Documentation/dev-plugins.txt
@@ -838,6 +838,63 @@
 }
 ----
 
+Plugins can receive a bean object for each of the gerrit ssh and the REST API
+commands by implementing BeanParseListener interface and registering it to a
+command class name in the plugin module's `configure()` method. The below
+example shows a plugin that always limits the number of projects returned
+by the ls-projects SSH command.
+
+[source, java]
+----
+protected static class PluginModule extends AbstractModule {
+  @Override
+  public void configure() {
+    bind(DynamicOptions.DynamicBean.class)
+        .annotatedWith(Exports.named(ListProjectsCommand.class))
+        .to(ListProjectsCommandBeanListener.class);
+  }
+
+  protected static class ListProjectsCommandBeanListener
+      implements DynamicOptions.BeanParseListener {
+    @Override
+    public void onBeanParseStart(String plugin, Object bean) {
+      ListProjectsCommand command = (ListProjectsCommand) bean;
+      command.impl.setLimit(1);
+    }
+
+    @Override
+    public void onBeanParseEnd(String plugin, Object bean) {}
+  }
+}
+----
+
+The below example shows a plugin that always limits the number of projects
+returned by the /projects/ REST API.
+
+[source, java]
+----
+protected static class PluginModule extends AbstractModule {
+  @Override
+  public void configure() {
+    bind(DynamicOptions.DynamicBean.class)
+        .annotatedWith(Exports.named(ListProjects.class))
+        .to(ListProjectsBeanListener.class);
+  }
+
+  protected static class ListProjectsBeanListener
+      implements DynamicOptions.BeanParseListener {
+    @Override
+    public void onBeanParseStart(String plugin, Object bean) {
+      ListProjects listProjects = (ListProjects) bean;
+      listProjects.setLimit(1);
+    }
+
+    @Override
+    public void onBeanParseEnd(String plugin, Object bean) {}
+  }
+}
+----
+
 === Calling Command Options ===
 
 Within an OptionHandler, during the processing of an option, plugins can
@@ -899,7 +956,7 @@
 [[query_attributes]]
 == Change Attributes
 
-==== ChangePluginDefinedInfoFactory
+=== ChangePluginDefinedInfoFactory
 
 Plugins can provide additional attributes to be returned from the Get Change and
 Query Change APIs by implementing the `ChangePluginDefinedInfoFactory` interface
diff --git a/Documentation/intro-user.txt b/Documentation/intro-user.txt
index 0408d5d..dac1c6b 100644
--- a/Documentation/intro-user.txt
+++ b/Documentation/intro-user.txt
@@ -459,7 +459,7 @@
 push permission] on the destination branch.
 
 The move operation will not update the change's parent and users will have
-to link:#rebase[rebase] the change. Also, merge commits cannot be moved.
+to link:#rebase[rebase] the change.
 
 [[abandon]]
 [[restore]]
diff --git a/Documentation/logs.txt b/Documentation/logs.txt
index ba370b1..e120fdd 100644
--- a/Documentation/logs.txt
+++ b/Documentation/logs.txt
@@ -56,6 +56,11 @@
   CPU time in kernel mode is `total_cpu - user_cpu`.
 * `memory`: memory allocated in bytes to execute command. -1 if the JVM does
   not support this metric.
+* `command status`: the overall result of the git command over HTTP. Currently
+   populated only for the transfer phase of `git-upload-pack` commands.
+   Possible values:
+** `-1`: The `git-upload-pack` transfer was ultimately not successful
+** `0`: The `git-upload-pack` transfer was ultimately successful
 
 Example:
 ```
diff --git a/Documentation/pgm-reindex.txt b/Documentation/pgm-reindex.txt
index 5167277..5392564 100644
--- a/Documentation/pgm-reindex.txt
+++ b/Documentation/pgm-reindex.txt
@@ -20,7 +20,8 @@
 
 == OPTIONS
 --threads::
-	Number of threads to use for indexing.
+	Number of threads to use for indexing. Default is
+	link:config-gerrit.html#index.batchThreads[index.batchThreads]
 
 --changes-schema-version::
 	Schema version to reindex; default is most recent version.
diff --git a/Documentation/rest-api-projects.txt b/Documentation/rest-api-projects.txt
index 8ecc7bc..eee3d3e 100644
--- a/Documentation/rest-api-projects.txt
+++ b/Documentation/rest-api-projects.txt
@@ -421,11 +421,11 @@
 ----
 
 The `/projects/` URL also accepts a start integer in the `start`
-parameter. The results will skip `start` groups from project list.
+parameter. The results will skip `start` projects from project list.
 
 Query 25 projects starting from index 50.
 ----
-  GET /groups/?query=<query>&limit=25&start=50 HTTP/1.0
+  GET /projects/?query=<query>&limit=25&start=50 HTTP/1.0
 ----
 
 [[project-query-options]]
diff --git a/Documentation/user-dashboards.txt b/Documentation/user-dashboards.txt
index e64d625..364b0d9 100644
--- a/Documentation/user-dashboards.txt
+++ b/Documentation/user-dashboards.txt
@@ -12,7 +12,7 @@
 
 Dashboards are available via URLs like:
 ----
-  /#/dashboard/?title=Custom+View&To+Review=reviewer:john.doe@example.com&Pending+In+myproject=project:myproject+is:open
+  /dashboard/?title=Custom+View&To+Review=reviewer:john.doe@example.com&Pending+In+myproject=project:myproject+is:open
 ----
 This opens a view showing the title "Custom View" with two sections,
 "To Review" and "Pending in myproject":
@@ -51,7 +51,7 @@
 to changes for the current user:
 
 ----
-  /#/dashboard/?title=Mine&foreach=owner:self&My+Pending=is:open&My+Merged=is:merged
+  /dashboard/?title=Mine&foreach=owner:self&My+Pending=is:open&My+Merged=is:merged
 ----
 
 
diff --git a/java/com/google/gerrit/acceptance/GerritServer.java b/java/com/google/gerrit/acceptance/GerritServer.java
index f2cc9d1..d1e12f8 100644
--- a/java/com/google/gerrit/acceptance/GerritServer.java
+++ b/java/com/google/gerrit/acceptance/GerritServer.java
@@ -52,6 +52,7 @@
 import com.google.gerrit.server.config.SitePath;
 import com.google.gerrit.server.experiments.ConfigExperimentFeatures;
 import com.google.gerrit.server.git.receive.AsyncReceiveCommits;
+import com.google.gerrit.server.index.options.AutoFlush;
 import com.google.gerrit.server.schema.JdbcAccountPatchReviewStore;
 import com.google.gerrit.server.ssh.NoSshModule;
 import com.google.gerrit.server.util.ReplicaUtil;
@@ -429,7 +430,8 @@
         "accountPatchReviewDb", null, "url", JdbcAccountPatchReviewStore.TEST_IN_MEMORY_URL);
     daemon.setEnableHttpd(desc.httpd());
     daemon.setLuceneModule(
-        LuceneIndexModule.singleVersionAllLatest(0, ReplicaUtil.isReplica(baseConfig)));
+        LuceneIndexModule.singleVersionAllLatest(
+            0, ReplicaUtil.isReplica(baseConfig), AutoFlush.ENABLED));
     daemon.setDatabaseForTesting(
         ImmutableList.of(
             new InMemoryTestingDatabaseModule(cfg, site, inMemoryRepoManager),
diff --git a/java/com/google/gerrit/httpd/GitOverHttpServlet.java b/java/com/google/gerrit/httpd/GitOverHttpServlet.java
index 9736652..06f96c5 100644
--- a/java/com/google/gerrit/httpd/GitOverHttpServlet.java
+++ b/java/com/google/gerrit/httpd/GitOverHttpServlet.java
@@ -14,11 +14,15 @@
 
 package com.google.gerrit.httpd;
 
+import static javax.servlet.http.HttpServletResponse.SC_INTERNAL_SERVER_ERROR;
+import static org.eclipse.jgit.http.server.GitSmartHttpTools.sendError;
+
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.cache.Cache;
 import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.data.Capable;
 import com.google.gerrit.entities.Project;
 import com.google.gerrit.extensions.registration.DynamicSet;
@@ -54,6 +58,7 @@
 import com.google.inject.TypeLiteral;
 import com.google.inject.name.Named;
 import java.io.IOException;
+import java.text.MessageFormat;
 import java.time.Duration;
 import java.util.Arrays;
 import java.util.Collections;
@@ -70,10 +75,13 @@
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpServletResponseWrapper;
+import org.eclipse.jgit.errors.PackProtocolException;
 import org.eclipse.jgit.errors.RepositoryNotFoundException;
 import org.eclipse.jgit.http.server.GitServlet;
 import org.eclipse.jgit.http.server.GitSmartHttpTools;
+import org.eclipse.jgit.http.server.HttpServerText;
 import org.eclipse.jgit.http.server.ServletUtils;
+import org.eclipse.jgit.http.server.UploadPackErrorHandler;
 import org.eclipse.jgit.http.server.resolver.AsIsFileService;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Repository;
@@ -100,6 +108,23 @@
   private static final String ID_CACHE = "adv_bases";
 
   public static final String URL_REGEX;
+  public static final String GIT_COMMAND_STATUS_HEADER = "X-git-command-status";
+
+  private enum GIT_COMMAND_STATUS {
+    OK(0),
+    FAIL(-1);
+
+    private final int exitStatus;
+
+    GIT_COMMAND_STATUS(int exitStatus) {
+      this.exitStatus = exitStatus;
+    }
+
+    @Override
+    public String toString() {
+      return Integer.toString(exitStatus);
+    }
+  }
 
   static {
     StringBuilder url = new StringBuilder();
@@ -212,12 +237,14 @@
       Resolver resolver,
       UploadFactory upload,
       UploadFilter uploadFilter,
+      GerritUploadPackErrorHandler uploadPackErrorHandler,
       ReceivePackFactory<HttpServletRequest> receive,
       ReceiveFilter receiveFilter) {
     setRepositoryResolver(resolver);
     setAsIsFileService(AsIsFileService.DISABLED);
 
     setUploadPackFactory(upload);
+    setUploadPackErrorHandler(uploadPackErrorHandler);
     addUploadPackFilter(uploadFilter);
 
     setReceivePackFactory(receive);
@@ -456,6 +483,35 @@
     public void destroy() {}
   }
 
+  static class GerritUploadPackErrorHandler implements UploadPackErrorHandler {
+    private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
+    @Override
+    public void upload(HttpServletRequest req, HttpServletResponse rsp, UploadPackRunnable r)
+        throws IOException {
+      rsp.setHeader(GIT_COMMAND_STATUS_HEADER, GIT_COMMAND_STATUS.FAIL.toString());
+      try {
+        r.upload();
+        rsp.setHeader(GIT_COMMAND_STATUS_HEADER, GIT_COMMAND_STATUS.OK.toString());
+      } catch (ServiceMayNotContinueException e) {
+        if (!e.isOutput() && !rsp.isCommitted()) {
+          rsp.reset();
+          sendError(req, rsp, e.getStatusCode(), e.getMessage());
+        }
+      } catch (Throwable e) {
+        logger.atSevere().withCause(e).log(
+            MessageFormat.format(
+                HttpServerText.get().internalErrorDuringUploadPack,
+                ServletUtils.getRepository(req)));
+        if (!rsp.isCommitted()) {
+          rsp.reset();
+          String msg = e instanceof PackProtocolException ? e.getMessage() : null;
+          sendError(req, rsp, SC_INTERNAL_SERVER_ERROR, msg);
+        }
+      }
+    }
+  }
+
   static class ReceiveFactory implements ReceivePackFactory<HttpServletRequest> {
     private final AsyncReceiveCommits.Factory factory;
     private final Provider<CurrentUser> userProvider;
diff --git a/java/com/google/gerrit/httpd/init/WebAppInitializer.java b/java/com/google/gerrit/httpd/init/WebAppInitializer.java
index d03340b..2ed342f 100644
--- a/java/com/google/gerrit/httpd/init/WebAppInitializer.java
+++ b/java/com/google/gerrit/httpd/init/WebAppInitializer.java
@@ -81,6 +81,7 @@
 import com.google.gerrit.server.index.IndexModule;
 import com.google.gerrit.server.index.OnlineUpgrader;
 import com.google.gerrit.server.index.VersionManager;
+import com.google.gerrit.server.index.options.AutoFlush;
 import com.google.gerrit.server.mail.SignedTokenEmailTokenVerifier;
 import com.google.gerrit.server.mail.receive.MailReceiver;
 import com.google.gerrit.server.mail.send.SmtpEmailSender;
@@ -361,7 +362,7 @@
 
   private Module createIndexModule() {
     if (indexType.isLucene()) {
-      return LuceneIndexModule.latestVersion(false);
+      return LuceneIndexModule.latestVersion(false, AutoFlush.ENABLED);
     } else if (indexType.isElasticsearch()) {
       return ElasticIndexModule.latestVersion(false);
     } else {
diff --git a/java/com/google/gerrit/httpd/plugins/PluginServletContext.java b/java/com/google/gerrit/httpd/plugins/PluginServletContext.java
index 40083e4..5a8fa31 100644
--- a/java/com/google/gerrit/httpd/plugins/PluginServletContext.java
+++ b/java/com/google/gerrit/httpd/plugins/PluginServletContext.java
@@ -199,6 +199,11 @@
       String v = Version.getVersion();
       return "Gerrit Code Review/" + (v != null ? v : "dev");
     }
+
+    @Override
+    public String getVirtualServerName() {
+      return null;
+    }
   }
 
   interface API {
@@ -255,5 +260,7 @@
     int getMinorVersion();
 
     String getServerInfo();
+
+    String getVirtualServerName();
   }
 }
diff --git a/java/com/google/gerrit/lucene/AbstractLuceneIndex.java b/java/com/google/gerrit/lucene/AbstractLuceneIndex.java
index 5392ab4..1e6ccac 100644
--- a/java/com/google/gerrit/lucene/AbstractLuceneIndex.java
+++ b/java/com/google/gerrit/lucene/AbstractLuceneIndex.java
@@ -45,6 +45,7 @@
 import com.google.gerrit.index.query.ResultSet;
 import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.index.IndexUtils;
+import com.google.gerrit.server.index.options.AutoFlush;
 import com.google.gerrit.server.logging.LoggingContextAwareExecutorService;
 import com.google.gerrit.server.logging.LoggingContextAwareScheduledExecutorService;
 import java.io.IOException;
@@ -105,6 +106,7 @@
   private final ReferenceManager<IndexSearcher> searcherManager;
   private final ControlledRealTimeReopenThread<IndexSearcher> reopenThread;
   private final Set<NrtFuture> notDoneNrtFutures;
+  private final AutoFlush autoFlush;
   private ScheduledExecutorService autoCommitExecutor;
 
   AbstractLuceneIndex(
@@ -115,13 +117,15 @@
       ImmutableSet<String> skipFields,
       String subIndex,
       GerritIndexWriterConfig writerConfig,
-      SearcherFactory searcherFactory)
+      SearcherFactory searcherFactory,
+      AutoFlush autoFlush)
       throws IOException {
     this.schema = schema;
     this.sitePaths = sitePaths;
     this.dir = dir;
     this.name = name;
     this.skipFields = skipFields;
+    this.autoFlush = autoFlush;
     String index = Joiner.on('_').skipNulls().join(name, subIndex);
     long commitPeriod = writerConfig.getCommitWithinMs();
 
@@ -215,7 +219,9 @@
           }
         });
 
-    reopenThread.start();
+    if (autoFlush.equals(AutoFlush.ENABLED)) {
+      reopenThread.start();
+    }
   }
 
   @Override
@@ -484,6 +490,9 @@
     }
 
     private boolean isGenAvailableNowForCurrentSearcher() {
+      if (autoFlush.equals(AutoFlush.DISABLED)) {
+        return true;
+      }
       try {
         return reopenThread.waitForGeneration(gen, 0);
       } catch (InterruptedException e) {
diff --git a/java/com/google/gerrit/lucene/ChangeSubIndex.java b/java/com/google/gerrit/lucene/ChangeSubIndex.java
index 43daf25..36f800f 100644
--- a/java/com/google/gerrit/lucene/ChangeSubIndex.java
+++ b/java/com/google/gerrit/lucene/ChangeSubIndex.java
@@ -34,6 +34,7 @@
 import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gerrit.server.index.change.ChangeIndex;
+import com.google.gerrit.server.index.options.AutoFlush;
 import com.google.gerrit.server.query.change.ChangeData;
 import java.io.IOException;
 import java.nio.file.Path;
@@ -52,7 +53,8 @@
       Path path,
       ImmutableSet<String> skipFields,
       GerritIndexWriterConfig writerConfig,
-      SearcherFactory searcherFactory)
+      SearcherFactory searcherFactory,
+      AutoFlush autoFlush)
       throws IOException {
     this(
         schema,
@@ -61,7 +63,8 @@
         path.getFileName().toString(),
         skipFields,
         writerConfig,
-        searcherFactory);
+        searcherFactory,
+        autoFlush);
   }
 
   ChangeSubIndex(
@@ -71,9 +74,19 @@
       String subIndex,
       ImmutableSet<String> skipFields,
       GerritIndexWriterConfig writerConfig,
-      SearcherFactory searcherFactory)
+      SearcherFactory searcherFactory,
+      AutoFlush autoFlush)
       throws IOException {
-    super(schema, sitePaths, dir, NAME, skipFields, subIndex, writerConfig, searcherFactory);
+    super(
+        schema,
+        sitePaths,
+        dir,
+        NAME,
+        skipFields,
+        subIndex,
+        writerConfig,
+        searcherFactory,
+        autoFlush);
   }
 
   @Override
diff --git a/java/com/google/gerrit/lucene/LuceneAccountIndex.java b/java/com/google/gerrit/lucene/LuceneAccountIndex.java
index 242cffd..87b7cce 100644
--- a/java/com/google/gerrit/lucene/LuceneAccountIndex.java
+++ b/java/com/google/gerrit/lucene/LuceneAccountIndex.java
@@ -36,6 +36,7 @@
 import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.index.IndexUtils;
 import com.google.gerrit.server.index.account.AccountIndex;
+import com.google.gerrit.server.index.options.AutoFlush;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 import com.google.inject.assistedinject.Assisted;
@@ -94,7 +95,8 @@
       @GerritServerConfig Config cfg,
       SitePaths sitePaths,
       Provider<AccountCache> accountCache,
-      @Assisted Schema<AccountState> schema)
+      @Assisted Schema<AccountState> schema,
+      AutoFlush autoFlush)
       throws IOException {
     super(
         schema,
@@ -104,7 +106,8 @@
         ImmutableSet.of(),
         null,
         new GerritIndexWriterConfig(cfg, ACCOUNTS),
-        new SearcherFactory());
+        new SearcherFactory(),
+        autoFlush);
     this.accountCache = accountCache;
 
     indexWriterConfig = new GerritIndexWriterConfig(cfg, ACCOUNTS);
diff --git a/java/com/google/gerrit/lucene/LuceneChangeIndex.java b/java/com/google/gerrit/lucene/LuceneChangeIndex.java
index c3d4440..201c4a3 100644
--- a/java/com/google/gerrit/lucene/LuceneChangeIndex.java
+++ b/java/com/google/gerrit/lucene/LuceneChangeIndex.java
@@ -65,6 +65,7 @@
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gerrit.server.index.change.ChangeIndex;
 import com.google.gerrit.server.index.change.ChangeIndexRewriter;
+import com.google.gerrit.server.index.options.AutoFlush;
 import com.google.gerrit.server.project.SubmitRuleOptions;
 import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gerrit.server.query.change.ChangeDataSource;
@@ -183,7 +184,8 @@
       SitePaths sitePaths,
       @IndexExecutor(INTERACTIVE) ListeningExecutorService executor,
       ChangeData.Factory changeDataFactory,
-      @Assisted Schema<ChangeData> schema)
+      @Assisted Schema<ChangeData> schema,
+      AutoFlush autoFlush)
       throws IOException {
     this.executor = executor;
     this.changeDataFactory = changeDataFactory;
@@ -208,7 +210,8 @@
               "ramOpen",
               skipFields,
               openConfig,
-              searcherFactory);
+              searcherFactory,
+              autoFlush);
       closedIndex =
           new ChangeSubIndex(
               schema,
@@ -217,7 +220,8 @@
               "ramClosed",
               skipFields,
               closedConfig,
-              searcherFactory);
+              searcherFactory,
+              autoFlush);
     } else {
       Path dir = LuceneVersionManager.getDir(sitePaths, CHANGES, schema);
       openIndex =
@@ -227,7 +231,8 @@
               dir.resolve(CHANGES_OPEN),
               skipFields,
               openConfig,
-              searcherFactory);
+              searcherFactory,
+              autoFlush);
       closedIndex =
           new ChangeSubIndex(
               schema,
@@ -235,7 +240,8 @@
               dir.resolve(CHANGES_CLOSED),
               skipFields,
               closedConfig,
-              searcherFactory);
+              searcherFactory,
+              autoFlush);
     }
 
     idField = this.schema.useLegacyNumericFields() ? LEGACY_ID : LEGACY_ID_STR;
diff --git a/java/com/google/gerrit/lucene/LuceneGroupIndex.java b/java/com/google/gerrit/lucene/LuceneGroupIndex.java
index 5cad588..816739b 100644
--- a/java/com/google/gerrit/lucene/LuceneGroupIndex.java
+++ b/java/com/google/gerrit/lucene/LuceneGroupIndex.java
@@ -33,6 +33,7 @@
 import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.index.IndexUtils;
 import com.google.gerrit.server.index.group.GroupIndex;
+import com.google.gerrit.server.index.options.AutoFlush;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 import com.google.inject.assistedinject.Assisted;
@@ -84,7 +85,8 @@
       @GerritServerConfig Config cfg,
       SitePaths sitePaths,
       Provider<GroupCache> groupCache,
-      @Assisted Schema<InternalGroup> schema)
+      @Assisted Schema<InternalGroup> schema,
+      AutoFlush autoFlush)
       throws IOException {
     super(
         schema,
@@ -94,7 +96,8 @@
         ImmutableSet.of(),
         null,
         new GerritIndexWriterConfig(cfg, GROUPS),
-        new SearcherFactory());
+        new SearcherFactory(),
+        autoFlush);
     this.groupCache = groupCache;
 
     indexWriterConfig = new GerritIndexWriterConfig(cfg, GROUPS);
diff --git a/java/com/google/gerrit/lucene/LuceneIndexModule.java b/java/com/google/gerrit/lucene/LuceneIndexModule.java
index 302a2da..73256b1 100644
--- a/java/com/google/gerrit/lucene/LuceneIndexModule.java
+++ b/java/com/google/gerrit/lucene/LuceneIndexModule.java
@@ -14,6 +14,7 @@
 
 package com.google.gerrit.lucene;
 
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableMap;
 import com.google.gerrit.index.IndexConfig;
 import com.google.gerrit.index.project.ProjectIndex;
@@ -23,30 +24,48 @@
 import com.google.gerrit.server.index.account.AccountIndex;
 import com.google.gerrit.server.index.change.ChangeIndex;
 import com.google.gerrit.server.index.group.GroupIndex;
+import com.google.gerrit.server.index.options.AutoFlush;
 import java.util.Map;
 import org.apache.lucene.search.BooleanQuery;
 import org.eclipse.jgit.lib.Config;
 
 public class LuceneIndexModule extends AbstractIndexModule {
-  public static LuceneIndexModule singleVersionAllLatest(int threads, boolean slave) {
-    return new LuceneIndexModule(ImmutableMap.of(), threads, slave);
+  private final AutoFlush autoFlush;
+
+  public static LuceneIndexModule singleVersionAllLatest(
+      int threads, boolean slave, AutoFlush autoFlush) {
+    return new LuceneIndexModule(ImmutableMap.of(), threads, slave, autoFlush);
+  }
+
+  @VisibleForTesting
+  public static LuceneIndexModule singleVersionWithExplicitVersions(
+      Map<String, Integer> versions, int threads, boolean slave) {
+    return new LuceneIndexModule(versions, threads, slave, AutoFlush.ENABLED);
   }
 
   public static LuceneIndexModule singleVersionWithExplicitVersions(
-      Map<String, Integer> versions, int threads, boolean slave) {
-    return new LuceneIndexModule(versions, threads, slave);
+      Map<String, Integer> versions, int threads, boolean slave, AutoFlush autoFlush) {
+    return new LuceneIndexModule(versions, threads, slave, autoFlush);
   }
 
-  public static LuceneIndexModule latestVersion(boolean slave) {
-    return new LuceneIndexModule(null, 0, slave);
+  public static LuceneIndexModule latestVersion(boolean slave, AutoFlush autoFlush) {
+    return new LuceneIndexModule(null, 0, slave, autoFlush);
   }
 
   static boolean isInMemoryTest(Config cfg) {
     return cfg.getBoolean("index", "lucene", "testInmemory", false);
   }
 
-  private LuceneIndexModule(Map<String, Integer> singleVersions, int threads, boolean slave) {
+  private LuceneIndexModule(
+      Map<String, Integer> singleVersions, int threads, boolean slave, AutoFlush autoFlush) {
     super(singleVersions, threads, slave);
+    this.autoFlush = autoFlush;
+  }
+
+  @Override
+  protected void configure() {
+    super.configure();
+    bind(AutoFlush.class).toInstance(autoFlush);
   }
 
   @Override
diff --git a/java/com/google/gerrit/lucene/LuceneProjectIndex.java b/java/com/google/gerrit/lucene/LuceneProjectIndex.java
index 2a418ca..7e7aecb 100644
--- a/java/com/google/gerrit/lucene/LuceneProjectIndex.java
+++ b/java/com/google/gerrit/lucene/LuceneProjectIndex.java
@@ -32,6 +32,7 @@
 import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.index.IndexUtils;
+import com.google.gerrit.server.index.options.AutoFlush;
 import com.google.gerrit.server.project.ProjectCache;
 import com.google.gerrit.server.project.ProjectState;
 import com.google.inject.Inject;
@@ -84,7 +85,8 @@
       @GerritServerConfig Config cfg,
       SitePaths sitePaths,
       Provider<ProjectCache> projectCache,
-      @Assisted Schema<ProjectData> schema)
+      @Assisted Schema<ProjectData> schema,
+      AutoFlush autoFlush)
       throws IOException {
     super(
         schema,
@@ -94,7 +96,8 @@
         ImmutableSet.of(),
         null,
         new GerritIndexWriterConfig(cfg, PROJECTS),
-        new SearcherFactory());
+        new SearcherFactory(),
+        autoFlush);
     this.projectCache = projectCache;
 
     indexWriterConfig = new GerritIndexWriterConfig(cfg, PROJECTS);
diff --git a/java/com/google/gerrit/pgm/Daemon.java b/java/com/google/gerrit/pgm/Daemon.java
index 07bab24..266eb6f 100644
--- a/java/com/google/gerrit/pgm/Daemon.java
+++ b/java/com/google/gerrit/pgm/Daemon.java
@@ -89,6 +89,7 @@
 import com.google.gerrit.server.index.IndexModule;
 import com.google.gerrit.server.index.OnlineUpgrader;
 import com.google.gerrit.server.index.VersionManager;
+import com.google.gerrit.server.index.options.AutoFlush;
 import com.google.gerrit.server.mail.SignedTokenEmailTokenVerifier;
 import com.google.gerrit.server.mail.receive.MailReceiver;
 import com.google.gerrit.server.mail.send.SmtpEmailSender;
@@ -526,7 +527,7 @@
       return luceneModule;
     }
     if (indexType.isLucene()) {
-      return LuceneIndexModule.latestVersion(replica);
+      return LuceneIndexModule.latestVersion(replica, AutoFlush.ENABLED);
     }
     if (indexType.isElasticsearch()) {
       return ElasticIndexModule.latestVersion(replica);
diff --git a/java/com/google/gerrit/pgm/Reindex.java b/java/com/google/gerrit/pgm/Reindex.java
index 3935268..0872340 100644
--- a/java/com/google/gerrit/pgm/Reindex.java
+++ b/java/com/google/gerrit/pgm/Reindex.java
@@ -33,6 +33,7 @@
 import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.index.IndexModule;
 import com.google.gerrit.server.index.change.ChangeSchemaDefinitions;
+import com.google.gerrit.server.index.options.AutoFlush;
 import com.google.gerrit.server.plugins.PluginGuiceEnvironment;
 import com.google.gerrit.server.util.ReplicaUtil;
 import com.google.inject.Inject;
@@ -52,8 +53,10 @@
 import org.kohsuke.args4j.Option;
 
 public class Reindex extends SiteProgram {
-  @Option(name = "--threads", usage = "Number of threads to use for indexing")
-  private int threads = Runtime.getRuntime().availableProcessors();
+  @Option(
+      name = "--threads",
+      usage = "Number of threads to use for indexing. Default is index.batchThreads from config.")
+  private int threads = 0;
 
   @Option(
       name = "--changes-schema-version",
@@ -150,7 +153,9 @@
     Module indexModule;
     IndexType indexType = IndexModule.getIndexType(dbInjector);
     if (indexType.isLucene()) {
-      indexModule = LuceneIndexModule.singleVersionWithExplicitVersions(versions, threads, replica);
+      indexModule =
+          LuceneIndexModule.singleVersionWithExplicitVersions(
+              versions, threads, replica, AutoFlush.DISABLED);
     } else if (indexType.isElasticsearch()) {
       indexModule =
           ElasticIndexModule.singleVersionWithExplicitVersions(versions, threads, replica);
diff --git a/java/com/google/gerrit/pgm/http/jetty/HttpLog.java b/java/com/google/gerrit/pgm/http/jetty/HttpLog.java
index 56523dd..e88bb88 100644
--- a/java/com/google/gerrit/pgm/http/jetty/HttpLog.java
+++ b/java/com/google/gerrit/pgm/http/jetty/HttpLog.java
@@ -14,6 +14,8 @@
 
 package com.google.gerrit.pgm.http.jetty;
 
+import static com.google.gerrit.httpd.GitOverHttpServlet.GIT_COMMAND_STATUS_HEADER;
+
 import com.google.common.base.Strings;
 import com.google.gerrit.httpd.GetUserFilter;
 import com.google.gerrit.httpd.RequestMetricsFilter;
@@ -55,6 +57,7 @@
   protected static final String P_CPU_TOTAL = "Cpu-Total";
   protected static final String P_CPU_USER = "Cpu-User";
   protected static final String P_MEMORY = "Memory";
+  protected static final String P_COMMAND_STATUS = "Command-Status";
 
   private final AsyncAppender async;
 
@@ -117,6 +120,7 @@
     set(event, P_LATENCY, System.currentTimeMillis() - req.getTimeStamp());
     set(event, P_REFERER, req.getHeader("Referer"));
     set(event, P_USER_AGENT, req.getHeader("User-Agent"));
+    set(event, P_COMMAND_STATUS, rsp.getHeader(GIT_COMMAND_STATUS_HEADER));
 
     RequestMetricsFilter.Context ctx =
         (RequestMetricsFilter.Context) req.getAttribute(RequestMetricsFilter.METRICS_CONTEXT);
diff --git a/java/com/google/gerrit/pgm/http/jetty/HttpLogJsonLayout.java b/java/com/google/gerrit/pgm/http/jetty/HttpLogJsonLayout.java
index 5f4ec43..54c587b 100644
--- a/java/com/google/gerrit/pgm/http/jetty/HttpLogJsonLayout.java
+++ b/java/com/google/gerrit/pgm/http/jetty/HttpLogJsonLayout.java
@@ -14,6 +14,7 @@
 
 package com.google.gerrit.pgm.http.jetty;
 
+import static com.google.gerrit.pgm.http.jetty.HttpLog.P_COMMAND_STATUS;
 import static com.google.gerrit.pgm.http.jetty.HttpLog.P_CONTENT_LENGTH;
 import static com.google.gerrit.pgm.http.jetty.HttpLog.P_CPU_TOTAL;
 import static com.google.gerrit.pgm.http.jetty.HttpLog.P_CPU_USER;
@@ -56,6 +57,7 @@
     public String memory;
     public String referer;
     public String userAgent;
+    public String commandStatus;
 
     public HttpJsonLogEntry(LoggingEvent event) {
       this.host = getMdcString(event, P_HOST);
@@ -73,6 +75,7 @@
       this.memory = getMdcString(event, P_MEMORY);
       this.referer = getMdcString(event, P_REFERER);
       this.userAgent = getMdcString(event, P_USER_AGENT);
+      this.commandStatus = getMdcString(event, P_COMMAND_STATUS);
     }
   }
 }
diff --git a/java/com/google/gerrit/pgm/http/jetty/HttpLogLayout.java b/java/com/google/gerrit/pgm/http/jetty/HttpLogLayout.java
index e9e6866..ddc1b5e 100644
--- a/java/com/google/gerrit/pgm/http/jetty/HttpLogLayout.java
+++ b/java/com/google/gerrit/pgm/http/jetty/HttpLogLayout.java
@@ -80,6 +80,9 @@
     buf.append(' ');
     opt(buf, event, HttpLog.P_MEMORY);
 
+    buf.append(' ');
+    dq_opt(buf, event, HttpLog.P_COMMAND_STATUS);
+
     buf.append('\n');
     return buf.toString();
   }
diff --git a/java/com/google/gerrit/pgm/init/index/lucene/LuceneIndexModuleOnInit.java b/java/com/google/gerrit/pgm/init/index/lucene/LuceneIndexModuleOnInit.java
index 12a44dc..078e648 100644
--- a/java/com/google/gerrit/pgm/init/index/lucene/LuceneIndexModuleOnInit.java
+++ b/java/com/google/gerrit/pgm/init/index/lucene/LuceneIndexModuleOnInit.java
@@ -19,6 +19,7 @@
 import com.google.gerrit.pgm.init.index.IndexModuleOnInit;
 import com.google.gerrit.server.index.account.AccountIndex;
 import com.google.gerrit.server.index.group.GroupIndex;
+import com.google.gerrit.server.index.options.AutoFlush;
 import com.google.inject.AbstractModule;
 import com.google.inject.assistedinject.FactoryModuleBuilder;
 
@@ -36,5 +37,7 @@
             .build(GroupIndex.Factory.class));
 
     install(new IndexModuleOnInit());
+
+    bind(AutoFlush.class).toInstance(AutoFlush.DISABLED);
   }
 }
diff --git a/java/com/google/gerrit/server/DynamicOptions.java b/java/com/google/gerrit/server/DynamicOptions.java
index db0aa70..7f9fbd2 100644
--- a/java/com/google/gerrit/server/DynamicOptions.java
+++ b/java/com/google/gerrit/server/DynamicOptions.java
@@ -225,7 +225,7 @@
     Class<?> beanClass =
         (bean instanceof BeanReceiver)
             ? ((BeanReceiver) bean).getExportedBeanReceiver()
-            : getClass();
+            : bean.getClass();
     for (String plugin : dynamicBeans.plugins()) {
       Provider<DynamicBean> provider =
           dynamicBeans.byPlugin(plugin).get(beanClass.getCanonicalName());
diff --git a/java/com/google/gerrit/server/events/EventGsonProvider.java b/java/com/google/gerrit/server/events/EventGsonProvider.java
index 27be2f3..bd784cf 100644
--- a/java/com/google/gerrit/server/events/EventGsonProvider.java
+++ b/java/com/google/gerrit/server/events/EventGsonProvider.java
@@ -29,8 +29,8 @@
         .registerTypeAdapter(Event.class, new EventDeserializer())
         .registerTypeAdapter(Supplier.class, new SupplierSerializer())
         .registerTypeAdapter(Supplier.class, new SupplierDeserializer())
-        .registerTypeAdapter(Project.NameKey.class, new ProjectNameKeyAdapter())
         .registerTypeAdapterFactory(EntitiesAdapterFactory.create())
+        .registerTypeHierarchyAdapter(Project.NameKey.class, new ProjectNameKeyAdapter())
         .create();
   }
 }
diff --git a/java/com/google/gerrit/server/git/PermissionAwareReadOnlyRefDatabase.java b/java/com/google/gerrit/server/git/PermissionAwareReadOnlyRefDatabase.java
index b7dc2b3..7950dc6 100644
--- a/java/com/google/gerrit/server/git/PermissionAwareReadOnlyRefDatabase.java
+++ b/java/com/google/gerrit/server/git/PermissionAwareReadOnlyRefDatabase.java
@@ -14,7 +14,6 @@
 
 package com.google.gerrit.server.git;
 
-import static java.util.stream.Collectors.toList;
 import static java.util.stream.Collectors.toMap;
 
 import com.google.common.base.Preconditions;
@@ -95,20 +94,11 @@
     return Iterables.getOnlyElement(result);
   }
 
+  // WARNING: This method is deprecated in JGit's RefDatabase and it will be removed on master.
+  // Do not add any logic here but rather enrich the getRefsByPrefix method below.
   @Override
   public Map<String, Ref> getRefs(String prefix) throws IOException {
-    List<Ref> refs = getDelegate().getRefDatabase().getRefsByPrefix(prefix);
-    if (refs.isEmpty()) {
-      return Collections.emptyMap();
-    }
-
-    Collection<Ref> result;
-    try {
-      result = forProject.filter(refs, getDelegate(), RefFilterOptions.defaults());
-    } catch (PermissionBackendException e) {
-      throw new IOException("", e);
-    }
-    return buildPrefixRefMap(prefix, result);
+    return buildPrefixRefMap(prefix, getRefsByPrefix(prefix));
   }
 
   private Map<String, Ref> buildPrefixRefMap(String prefix, Collection<Ref> refs) {
@@ -125,26 +115,18 @@
 
   @Override
   public List<Ref> getRefsByPrefix(String prefix) throws IOException {
-    Map<String, Ref> coarseRefs;
-    int lastSlash = prefix.lastIndexOf('/');
-    if (lastSlash == -1) {
-      coarseRefs = getRefs(ALL);
-    } else {
-      coarseRefs = getRefs(prefix.substring(0, lastSlash + 1));
+    List<Ref> refs = getDelegate().getRefDatabase().getRefsByPrefix(prefix);
+    if (refs.isEmpty()) {
+      return Collections.emptyList();
     }
 
-    List<Ref> result;
-    if (lastSlash + 1 == prefix.length()) {
-      result = coarseRefs.values().stream().collect(toList());
-    } else {
-      String p = prefix.substring(lastSlash + 1);
-      result =
-          coarseRefs.entrySet().stream()
-              .filter(e -> e.getKey().startsWith(p))
-              .map(e -> e.getValue())
-              .collect(toList());
+    Collection<Ref> result;
+    try {
+      result = forProject.filter(refs, getDelegate(), RefFilterOptions.defaults());
+    } catch (PermissionBackendException e) {
+      throw new IOException("", e);
     }
-    return Collections.unmodifiableList(result);
+    return result.stream().collect(Collectors.toList());
   }
 
   @Override
diff --git a/java/com/google/gerrit/server/git/meta/VersionedMetaData.java b/java/com/google/gerrit/server/git/meta/VersionedMetaData.java
index feb038a..ea594dd 100644
--- a/java/com/google/gerrit/server/git/meta/VersionedMetaData.java
+++ b/java/com/google/gerrit/server/git/meta/VersionedMetaData.java
@@ -217,6 +217,27 @@
   }
 
   /**
+   * Update this metadata branch, recording a new commit on its reference. This method mutates its
+   * receiver.
+   *
+   * @param update helper information to define the update that will occur.
+   * @param objInserter Shared object inserter.
+   * @param objReader Shared object reader.
+   * @param revWalk Shared rev walk.
+   * @return the commit that was created
+   * @throws IOException if there is a storage problem and the update cannot be executed as
+   *     requested or if it failed because of a concurrent update to the same reference
+   */
+  public RevCommit commit(
+      MetaDataUpdate update, ObjectInserter objInserter, ObjectReader objReader, RevWalk revWalk)
+      throws IOException {
+    try (BatchMetaDataUpdate batch = openUpdate(update, objInserter, objReader, revWalk)) {
+      batch.write(update.getCommitBuilder());
+      return batch.commit();
+    }
+  }
+
+  /**
    * Creates a new commit and a new ref based on this commit. This method mutates its receiver.
    *
    * @param update helper information to define the update that will occur.
@@ -263,11 +284,39 @@
    * @throws IOException if the update failed.
    */
   public BatchMetaDataUpdate openUpdate(MetaDataUpdate update) throws IOException {
+    return openUpdate(update, null, null, null);
+  }
+
+  /**
+   * Open a batch of updates to the same metadata ref.
+   *
+   * <p>This allows making multiple commits to a single metadata ref, at the end of which is a
+   * single ref update. For batching together updates to multiple refs (each consisting of one or
+   * more commits against their respective refs), create the {@link MetaDataUpdate} with a {@link
+   * BatchRefUpdate}.
+   *
+   * <p>A ref update produced by this {@link BatchMetaDataUpdate} is only committed if there is no
+   * associated {@link BatchRefUpdate}. As a result, the configured ref updated event is not fired
+   * if there is an associated batch.
+   *
+   * <p>If object inserter, reader and revwalk are provided, then the updates are not flushed,
+   * allowing callers the flexibility to flush only once after several updates.
+   *
+   * @param update helper info about the update.
+   * @param objInserter Shared object inserter.
+   * @param objReader Shared object reader.
+   * @param revWalk Shared rev walk.
+   * @throws IOException if the update failed.
+   */
+  public BatchMetaDataUpdate openUpdate(
+      MetaDataUpdate update, ObjectInserter objInserter, ObjectReader objReader, RevWalk revWalk)
+      throws IOException {
     final Repository db = update.getRepository();
 
-    inserter = db.newObjectInserter();
-    reader = inserter.newReader();
-    final RevWalk rw = new RevWalk(reader);
+    inserter = objInserter == null ? db.newObjectInserter() : objInserter;
+    reader = objReader == null ? inserter.newReader() : objReader;
+    final RevWalk rw = revWalk == null ? new RevWalk(reader) : revWalk;
+
     final RevTree tree = revision != null ? rw.parseTree(revision) : null;
     newTree = readTree(tree);
     return new BatchMetaDataUpdate() {
@@ -379,13 +428,16 @@
       public void close() {
         newTree = null;
 
-        rw.close();
-        if (inserter != null) {
+        if (revWalk == null) {
+          rw.close();
+        }
+
+        if (objInserter == null && inserter != null) {
           inserter.close();
           inserter = null;
         }
 
-        if (reader != null) {
+        if (objReader == null && reader != null) {
           reader.close();
           reader = null;
         }
@@ -396,7 +448,9 @@
         BatchRefUpdate bru = update.getBatch();
         if (bru != null) {
           bru.addCommand(new ReceiveCommand(oldId.toObjectId(), newId.toObjectId(), refName));
-          inserter.flush();
+          if (objInserter == null) {
+            inserter.flush();
+          }
           revision = rw.parseCommit(newId);
           return revision;
         }
diff --git a/java/com/google/gerrit/server/git/receive/ReceiveCommits.java b/java/com/google/gerrit/server/git/receive/ReceiveCommits.java
index f35b3dd..1006c23 100644
--- a/java/com/google/gerrit/server/git/receive/ReceiveCommits.java
+++ b/java/com/google/gerrit/server/git/receive/ReceiveCommits.java
@@ -2729,7 +2729,7 @@
     try (TraceTimer traceTimer = newTimer("readChangesForReplace")) {
       replaceByChange.values().stream()
           .map(r -> r.ontoChange)
-          .map(id -> notesFactory.create(project.getNameKey(), id))
+          .map(id -> notesFactory.create(repo, project.getNameKey(), id))
           .forEach(notes -> replaceByChange.get(notes.getChangeId()).notes = notes);
     }
   }
diff --git a/java/com/google/gerrit/server/index/IndexModule.java b/java/com/google/gerrit/server/index/IndexModule.java
index 6db00f5..17665c0 100644
--- a/java/com/google/gerrit/server/index/IndexModule.java
+++ b/java/com/google/gerrit/server/index/IndexModule.java
@@ -208,13 +208,14 @@
       return interactiveExecutor;
     }
     int threads = this.threads;
-    if (threads < 0) {
-      return MoreExecutors.newDirectExecutorService();
-    } else if (threads == 0) {
+    if (threads == 0) {
       threads =
           config.getInt(
               "index", null, "threads", Runtime.getRuntime().availableProcessors() / 2 + 1);
     }
+    if (threads < 0) {
+      return MoreExecutors.newDirectExecutorService();
+    }
     return MoreExecutors.listeningDecorator(
         workQueue.createQueue(threads, "Index-Interactive", true));
   }
@@ -227,11 +228,13 @@
     if (batchExecutor != null) {
       return batchExecutor;
     }
-    int threads = config.getInt("index", null, "batchThreads", 0);
+    int threads = this.threads;
+    if (threads == 0) {
+      threads =
+          config.getInt("index", null, "batchThreads", Runtime.getRuntime().availableProcessors());
+    }
     if (threads < 0) {
       return MoreExecutors.newDirectExecutorService();
-    } else if (threads == 0) {
-      threads = Runtime.getRuntime().availableProcessors();
     }
     return MoreExecutors.listeningDecorator(workQueue.createQueue(threads, "Index-Batch", true));
   }
diff --git a/java/com/google/gerrit/server/index/change/AllChangesIndexer.java b/java/com/google/gerrit/server/index/change/AllChangesIndexer.java
index 75daa72..ab42e5a 100644
--- a/java/com/google/gerrit/server/index/change/AllChangesIndexer.java
+++ b/java/com/google/gerrit/server/index/change/AllChangesIndexer.java
@@ -134,6 +134,10 @@
         // splitting of repos into smaller parts reduced indexing time from 1.5 hours to 55 minutes
         // in 2020.
         int size = estimateSize(repo);
+        if (size == 0) {
+          pm.update(1);
+          continue;
+        }
         changeCount += size;
         int slices = 1 + size / PROJECT_SLICE_MAX_REFS;
         if (slices > 1) {
diff --git a/java/com/google/gerrit/server/index/options/AutoFlush.java b/java/com/google/gerrit/server/index/options/AutoFlush.java
new file mode 100644
index 0000000..7b82edb
--- /dev/null
+++ b/java/com/google/gerrit/server/index/options/AutoFlush.java
@@ -0,0 +1,20 @@
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.index.options;
+
+public enum AutoFlush {
+  ENABLED,
+  DISABLED
+}
diff --git a/java/com/google/gerrit/server/mail/send/OutgoingEmail.java b/java/com/google/gerrit/server/mail/send/OutgoingEmail.java
index f5fb6b0..746a07a 100644
--- a/java/com/google/gerrit/server/mail/send/OutgoingEmail.java
+++ b/java/com/google/gerrit/server/mail/send/OutgoingEmail.java
@@ -141,7 +141,8 @@
             // drop them from the recipient lists.
             //
             logger.atFine().log(
-                "Not CCing email sender %s because the email strategy of this user is not %s but %s",
+                "Not CCing email sender %s because the email strategy of this user is not %s but"
+                    + " %s",
                 fromUser.get().account().id(),
                 CC_ON_OWN_COMMENTS,
                 senderPrefs != null ? senderPrefs.getEmailStrategy() : null);
@@ -421,9 +422,13 @@
    * username. If no username is set, this function returns null.
    *
    * @param accountId user to fetch.
-   * @return name/email of account, username, or null if unset.
+   * @return name/email of account, username, or null if unset or the accountId is null.
    */
-  protected String getUserNameEmailFor(Account.Id accountId) {
+  protected String getUserNameEmailFor(@Nullable Account.Id accountId) {
+    if (accountId == null) {
+      return null;
+    }
+
     Optional<AccountState> accountState = args.accountCache.get(accountId);
     if (!accountState.isPresent()) {
       return null;
diff --git a/java/com/google/gerrit/server/notedb/AbstractChangeNotes.java b/java/com/google/gerrit/server/notedb/AbstractChangeNotes.java
index 63b6d61..74ecd68 100644
--- a/java/com/google/gerrit/server/notedb/AbstractChangeNotes.java
+++ b/java/com/google/gerrit/server/notedb/AbstractChangeNotes.java
@@ -138,6 +138,15 @@
   }
 
   public T load() {
+    try (Repository repo = args.repoManager.openRepository(getProjectName())) {
+      load(repo);
+      return self();
+    } catch (IOException e) {
+      throw new StorageException(e);
+    }
+  }
+
+  public T load(Repository repo) {
     if (loaded) {
       return self();
     }
@@ -146,7 +155,6 @@
       throw new StorageException("Reading from NoteDb is disabled");
     }
     try (Timer0.Context timer = args.metrics.readLatency.start();
-        Repository repo = args.repoManager.openRepository(getProjectName());
         // Call openHandle even if reading is disabled, to trigger
         // auto-rebuilding before this object may get passed to a ChangeUpdate.
         LoadHandle handle = openHandle(repo, revision)) {
diff --git a/java/com/google/gerrit/server/notedb/ChangeNotes.java b/java/com/google/gerrit/server/notedb/ChangeNotes.java
index 77d7bc0..1f6d718 100644
--- a/java/com/google/gerrit/server/notedb/ChangeNotes.java
+++ b/java/com/google/gerrit/server/notedb/ChangeNotes.java
@@ -67,12 +67,14 @@
 import java.sql.Timestamp;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.function.Predicate;
 import java.util.stream.Stream;
 import org.eclipse.jgit.errors.ConfigInvalidException;
+import org.eclipse.jgit.errors.RepositoryNotFoundException;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.Repository;
@@ -134,6 +136,22 @@
       return new ChangeNotes(args, newChange(project, changeId), true, null).load();
     }
 
+    public ChangeNotes create(Repository repository, Project.NameKey project, Change.Id changeId) {
+      checkArgument(project != null, "project is required");
+      return new ChangeNotes(args, newChange(project, changeId), true, null).load(repository);
+    }
+
+    /**
+     * Create change notes for a change that was loaded from index. This method should only be used
+     * when database access is harmful and potentially stale data from the index is acceptable.
+     *
+     * @param change change loaded from secondary index
+     * @return change notes
+     */
+    public ChangeNotes createFromIndexedChange(Change change) {
+      return new ChangeNotes(args, change, true, null);
+    }
+
     public ChangeNotes createForBatchUpdate(Change change, boolean shouldExist) {
       return new ChangeNotes(args, change, shouldExist, null).load();
     }
@@ -178,13 +196,14 @@
     }
 
     public List<ChangeNotes> create(
+        Repository repo,
         Project.NameKey project,
         Collection<Change.Id> changeIds,
         Predicate<ChangeNotes> predicate) {
       List<ChangeNotes> notes = new ArrayList<>();
       for (Change.Id cid : changeIds) {
         try {
-          ChangeNotes cn = create(project, cid);
+          ChangeNotes cn = create(repo, project, cid);
           if (cn.getChange() != null && predicate.test(cn)) {
             notes.add(cn);
           }
@@ -197,6 +216,28 @@
       return notes;
     }
 
+    /* TODO: This is now unused in the Gerrit code-base, however it is kept in the code
+    /* because it is a public method in a stable branch.
+     * It can be removed in master branch where we have more flexibility to change the API
+     * interface.
+     */
+    public List<ChangeNotes> create(
+        Project.NameKey project,
+        Collection<Change.Id> changeIds,
+        Predicate<ChangeNotes> predicate) {
+      try (Repository repo = args.repoManager.openRepository(project)) {
+        return create(repo, project, changeIds, predicate);
+      } catch (RepositoryNotFoundException e) {
+        // The repository does not exist, hence it does not contain
+        // any change.
+      } catch (IOException e) {
+        logger.atWarning().withCause(e).log(
+            "Unable to open project=%s when trying to retrieve changeId=%s from NoteDb",
+            project, changeIds);
+      }
+      return Collections.emptyList();
+    }
+
     public ListMultimap<Project.NameKey, ChangeNotes> create(Predicate<ChangeNotes> predicate)
         throws IOException {
       ListMultimap<Project.NameKey, ChangeNotes> m =
diff --git a/java/com/google/gerrit/server/notedb/DraftCommentNotes.java b/java/com/google/gerrit/server/notedb/DraftCommentNotes.java
index 9b403e8..4988406 100644
--- a/java/com/google/gerrit/server/notedb/DraftCommentNotes.java
+++ b/java/com/google/gerrit/server/notedb/DraftCommentNotes.java
@@ -59,7 +59,7 @@
   }
 
   DraftCommentNotes(Args args, Change.Id changeId, Account.Id author, @Nullable Ref ref) {
-    super(args, changeId);
+    super(args, changeId, null);
     this.author = requireNonNull(author);
     this.ref = ref;
     if (ref != null) {
diff --git a/java/com/google/gerrit/server/notedb/RobotCommentNotes.java b/java/com/google/gerrit/server/notedb/RobotCommentNotes.java
index fe05643..d53b2ca 100644
--- a/java/com/google/gerrit/server/notedb/RobotCommentNotes.java
+++ b/java/com/google/gerrit/server/notedb/RobotCommentNotes.java
@@ -47,7 +47,7 @@
 
   @Inject
   RobotCommentNotes(Args args, @Assisted Change change) {
-    super(args, change.getId());
+    super(args, change.getId(), null);
     this.change = change;
   }
 
diff --git a/java/com/google/gerrit/server/permissions/DefaultRefFilter.java b/java/com/google/gerrit/server/permissions/DefaultRefFilter.java
index 10aa9cd..1b528d7 100644
--- a/java/com/google/gerrit/server/permissions/DefaultRefFilter.java
+++ b/java/com/google/gerrit/server/permissions/DefaultRefFilter.java
@@ -135,7 +135,7 @@
         return ImmutableList.of();
       }
       if (RefNames.isRefsChanges(refName)) {
-        boolean isChangeRefVisisble = canSeeSingleChangeRef(refName);
+        boolean isChangeRefVisisble = canSeeSingleChangeRef(repo, refName);
         if (isChangeRefVisisble) {
           logger.atFinest().log("Change ref %s is visible", refName);
           return refs;
@@ -371,7 +371,8 @@
    * with refs-in-wants is used as that enables Gerrit to skip traditional advertisement of all
    * visible refs.
    */
-  private boolean canSeeSingleChangeRef(String refName) throws PermissionBackendException {
+  private boolean canSeeSingleChangeRef(Repository repo, String refName)
+      throws PermissionBackendException {
     // We are treating just a single change ref. We are therefore not going through regular ref
     // filtering, but use NoteDb directly. This makes it so that we can always serve this ref
     // even if the change is not part of the set of most recent changes that
@@ -385,7 +386,7 @@
     }
     ChangeNotes notes;
     try {
-      notes = changeNotesFactory.create(projectState.getNameKey(), cId);
+      notes = changeNotesFactory.create(repo, projectState.getNameKey(), cId);
     } catch (StorageException e) {
       throw new PermissionBackendException("can't construct change notes", e);
     }
diff --git a/java/com/google/gerrit/server/query/change/InternalChangeQuery.java b/java/com/google/gerrit/server/query/change/InternalChangeQuery.java
index 6605c23..1012f4a 100644
--- a/java/com/google/gerrit/server/query/change/InternalChangeQuery.java
+++ b/java/com/google/gerrit/server/query/change/InternalChangeQuery.java
@@ -193,6 +193,7 @@
 
     List<ChangeNotes> notes =
         notesFactory.create(
+            repo,
             branch.project(),
             changeIds,
             cn -> {
diff --git a/java/com/google/gerrit/server/restapi/change/Move.java b/java/com/google/gerrit/server/restapi/change/Move.java
index 8ec394c..fc7e9f4 100644
--- a/java/com/google/gerrit/server/restapi/change/Move.java
+++ b/java/com/google/gerrit/server/restapi/change/Move.java
@@ -204,9 +204,6 @@
           RevWalk revWalk = new RevWalk(repo)) {
         RevCommit currPatchsetRevCommit =
             revWalk.parseCommit(psUtil.current(ctx.getNotes()).commitId());
-        if (currPatchsetRevCommit.getParentCount() > 1) {
-          throw new ResourceConflictException("Merge commit cannot be moved");
-        }
 
         ObjectId refId = repo.resolve(input.destinationBranch);
         // Check if destination ref exists in project repo
diff --git a/java/com/google/gerrit/server/restapi/project/GetAccess.java b/java/com/google/gerrit/server/restapi/project/GetAccess.java
index b572db3..a79439c 100644
--- a/java/com/google/gerrit/server/restapi/project/GetAccess.java
+++ b/java/com/google/gerrit/server/restapi/project/GetAccess.java
@@ -331,7 +331,7 @@
         }
         AccountGroup.UUID group = r.getGroup().getUUID();
         if (group != null) {
-          pInfo.rules.put(group.get(), info);
+          pInfo.rules.putIfAbsent(group.get(), info); // First entry for the group wins
           loadGroup(groups, group);
         }
       }
diff --git a/javatests/com/google/gerrit/acceptance/rest/DynamicOptionsBeanParseListenerIT.java b/javatests/com/google/gerrit/acceptance/rest/DynamicOptionsBeanParseListenerIT.java
new file mode 100644
index 0000000..39f1e8d
--- /dev/null
+++ b/javatests/com/google/gerrit/acceptance/rest/DynamicOptionsBeanParseListenerIT.java
@@ -0,0 +1,67 @@
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.acceptance.rest;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.gerrit.acceptance.AbstractDaemonTest;
+import com.google.gerrit.acceptance.RestResponse;
+import com.google.gerrit.extensions.annotations.Exports;
+import com.google.gerrit.json.OutputFormat;
+import com.google.gerrit.server.DynamicOptions;
+import com.google.gerrit.server.restapi.project.ListProjects;
+import com.google.gson.Gson;
+import com.google.gson.reflect.TypeToken;
+import com.google.inject.AbstractModule;
+import java.util.Map;
+import org.junit.Test;
+
+public class DynamicOptionsBeanParseListenerIT extends AbstractDaemonTest {
+  private static final Gson GSON = OutputFormat.JSON.newGson();
+
+  @Test
+  public void testBeanParseListener() throws Exception {
+    createProjectOverAPI("project1", project, true, null);
+    createProjectOverAPI("project2", project, true, null);
+    try (AutoCloseable ignored = installPlugin("my-plugin", PluginModule.class)) {
+      assertThat(getProjects(adminRestSession.get("/projects/"))).hasSize(1);
+    }
+  }
+
+  protected Map<String, Object> getProjects(RestResponse res) throws Exception {
+    res.assertOK();
+    return GSON.fromJson(res.getReader(), new TypeToken<Map<String, Object>>() {}.getType());
+  }
+
+  protected static class ListProjectsBeanListener implements DynamicOptions.BeanParseListener {
+    @Override
+    public void onBeanParseStart(String plugin, Object bean) {
+      ListProjects listProjects = (ListProjects) bean;
+      listProjects.setLimit(1);
+    }
+
+    @Override
+    public void onBeanParseEnd(String plugin, Object bean) {}
+  }
+
+  protected static class PluginModule extends AbstractModule {
+    @Override
+    public void configure() {
+      bind(DynamicOptions.DynamicBean.class)
+          .annotatedWith(Exports.named(ListProjects.class))
+          .to(ListProjectsBeanListener.class);
+    }
+  }
+}
diff --git a/javatests/com/google/gerrit/acceptance/rest/change/MoveChangeIT.java b/javatests/com/google/gerrit/acceptance/rest/change/MoveChangeIT.java
index e94b660..69f1d8e 100644
--- a/javatests/com/google/gerrit/acceptance/rest/change/MoveChangeIT.java
+++ b/javatests/com/google/gerrit/acceptance/rest/change/MoveChangeIT.java
@@ -174,11 +174,9 @@
     BranchNameKey newBranch =
         BranchNameKey.create(r1.getChange().change().getProject(), "moveTest");
     createBranch(newBranch);
-    ResourceConflictException thrown =
-        assertThrows(
-            ResourceConflictException.class,
-            () -> move(GitUtil.getChangeId(testRepo, c).get(), newBranch.branch()));
-    assertThat(thrown).hasMessageThat().contains("Merge commit cannot be moved");
+    String changeId = GitUtil.getChangeId(testRepo, c).get();
+    move(changeId, newBranch.branch());
+    assertThat(gApi.changes().id(changeId).get().branch).isEqualTo("moveTest");
   }
 
   @Test
diff --git a/javatests/com/google/gerrit/acceptance/rest/project/AccessIT.java b/javatests/com/google/gerrit/acceptance/rest/project/AccessIT.java
index ff4f203..4a9edba 100644
--- a/javatests/com/google/gerrit/acceptance/rest/project/AccessIT.java
+++ b/javatests/com/google/gerrit/acceptance/rest/project/AccessIT.java
@@ -23,6 +23,8 @@
 import static com.google.gerrit.testing.GerritJUnit.assertThrows;
 import static com.google.gerrit.truth.ConfigSubject.assertThat;
 import static com.google.gerrit.truth.MapSubject.assertThatMap;
+import static java.util.Arrays.asList;
+import static org.junit.Assert.assertEquals;
 
 import com.google.gerrit.acceptance.AbstractDaemonTest;
 import com.google.gerrit.acceptance.ExtensionRegistry;
@@ -63,6 +65,7 @@
 import com.google.gerrit.server.schema.GrantRevertPermission;
 import com.google.inject.Inject;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import org.eclipse.jgit.internal.storage.dfs.InMemoryRepository;
 import org.eclipse.jgit.junit.TestRepository;
@@ -949,6 +952,90 @@
     return gApi.projects().name(newProjectName.get());
   }
 
+  @Test
+  public void grantAllowAndDenyForSameGroup() throws Exception {
+    GroupReference registeredUsers = systemGroupBackend.getGroup(REGISTERED_USERS);
+    String access = "access";
+    List<String> allowThenDeny =
+        asList(registeredUsers.toConfigValue(), "deny " + registeredUsers.toConfigValue());
+    // Clone repository to forcefully add permission
+    TestRepository<InMemoryRepository> allProjectsRepo = cloneProject(allProjects, admin);
+
+    // Fetch permission ref
+    GitUtil.fetch(allProjectsRepo, "refs/meta/config:cfg");
+    allProjectsRepo.reset("cfg");
+
+    // Load current permissions
+    String config =
+        gApi.projects()
+            .name(allProjects.get())
+            .branch(RefNames.REFS_CONFIG)
+            .file(ProjectConfig.PROJECT_CONFIG)
+            .asString();
+
+    // Append and push allowThenDeny permissions
+    Config cfg = new Config();
+    cfg.fromText(config);
+    cfg.setStringList(access, AccessSection.HEADS, Permission.READ, allowThenDeny);
+    config = cfg.toText();
+    PushOneCommit push =
+        pushFactory.create(
+            admin.newIdent(), allProjectsRepo, "Subject", ProjectConfig.PROJECT_CONFIG, config);
+    push.to(RefNames.REFS_CONFIG).assertOkStatus();
+
+    ProjectAccessInfo pai = gApi.projects().name(allProjects.get()).access();
+    Map<String, AccessSectionInfo> local = pai.local;
+    AccessSectionInfo heads = local.get(AccessSection.HEADS);
+    Map<String, PermissionInfo> permissions = heads.permissions;
+    PermissionInfo read = permissions.get(Permission.READ);
+    Map<String, PermissionRuleInfo> rules = read.rules;
+    assertEquals(
+        rules.get(registeredUsers.getUUID().get()),
+        new PermissionRuleInfo(PermissionRuleInfo.Action.ALLOW, false));
+  }
+
+  @Test
+  public void grantDenyAndAllowForSameGroup() throws Exception {
+    GroupReference registeredUsers = systemGroupBackend.getGroup(REGISTERED_USERS);
+    String access = "access";
+    List<String> denyThenAllow =
+        asList("deny " + registeredUsers.toConfigValue(), registeredUsers.toConfigValue());
+    // Clone repository to forcefully add permission
+    TestRepository<InMemoryRepository> allProjectsRepo = cloneProject(allProjects, admin);
+
+    // Fetch permission ref
+    GitUtil.fetch(allProjectsRepo, "refs/meta/config:cfg");
+    allProjectsRepo.reset("cfg");
+
+    // Load current permissions
+    String config =
+        gApi.projects()
+            .name(allProjects.get())
+            .branch(RefNames.REFS_CONFIG)
+            .file(ProjectConfig.PROJECT_CONFIG)
+            .asString();
+
+    // Append and push denyThenAllow permissions
+    Config cfg = new Config();
+    cfg.fromText(config);
+    cfg.setStringList(access, AccessSection.HEADS, Permission.READ, denyThenAllow);
+    config = cfg.toText();
+    PushOneCommit push =
+        pushFactory.create(
+            admin.newIdent(), allProjectsRepo, "Subject", ProjectConfig.PROJECT_CONFIG, config);
+    push.to(RefNames.REFS_CONFIG).assertOkStatus();
+
+    ProjectAccessInfo pai = gApi.projects().name(allProjects.get()).access();
+    Map<String, AccessSectionInfo> local = pai.local;
+    AccessSectionInfo heads = local.get(AccessSection.HEADS);
+    Map<String, PermissionInfo> permissions = heads.permissions;
+    PermissionInfo read = permissions.get(Permission.READ);
+    Map<String, PermissionRuleInfo> rules = read.rules;
+    assertEquals(
+        rules.get(registeredUsers.getUUID().get()),
+        new PermissionRuleInfo(PermissionRuleInfo.Action.DENY, false));
+  }
+
   private ProjectAccessInput newProjectAccessInput() {
     ProjectAccessInput p = new ProjectAccessInput();
     p.add = new HashMap<>();
diff --git a/javatests/com/google/gerrit/acceptance/ssh/DynamicOptionsBeanParseListenerIT.java b/javatests/com/google/gerrit/acceptance/ssh/DynamicOptionsBeanParseListenerIT.java
new file mode 100644
index 0000000..0afdbc6
--- /dev/null
+++ b/javatests/com/google/gerrit/acceptance/ssh/DynamicOptionsBeanParseListenerIT.java
@@ -0,0 +1,69 @@
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.acceptance.ssh;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.gerrit.acceptance.AbstractDaemonTest;
+import com.google.gerrit.acceptance.NoHttpd;
+import com.google.gerrit.acceptance.UseSsh;
+import com.google.gerrit.extensions.annotations.Exports;
+import com.google.gerrit.server.DynamicOptions;
+import com.google.gerrit.sshd.commands.ListProjectsCommand;
+import com.google.inject.AbstractModule;
+import java.util.Arrays;
+import java.util.List;
+import org.junit.Test;
+
+@NoHttpd
+@UseSsh
+public class DynamicOptionsBeanParseListenerIT extends AbstractDaemonTest {
+
+  @Test
+  public void testBeanParseListener() throws Exception {
+    createProjectOverAPI("project1", project, true, null);
+    createProjectOverAPI("project2", project, true, null);
+    try (AutoCloseable ignored = installPlugin("my-plugin", PluginModule.class)) {
+      String output = adminSshSession.exec("gerrit ls-projects");
+      adminSshSession.assertSuccess();
+      assertThat(getProjects(output)).hasSize(1);
+    }
+  }
+
+  protected List<String> getProjects(String sshOutput) {
+    return Arrays.asList(sshOutput.split("\n"));
+  }
+
+  protected static class ListProjectsCommandBeanListener
+      implements DynamicOptions.BeanParseListener {
+    @Override
+    public void onBeanParseStart(String plugin, Object bean) {
+      ListProjectsCommand command = (ListProjectsCommand) bean;
+      command.impl.setLimit(1);
+    }
+
+    @Override
+    public void onBeanParseEnd(String plugin, Object bean) {}
+  }
+
+  protected static class PluginModule extends AbstractModule {
+    @Override
+    public void configure() {
+      bind(DynamicOptions.DynamicBean.class)
+          .annotatedWith(Exports.named(ListProjectsCommand.class))
+          .to(ListProjectsCommandBeanListener.class);
+    }
+  }
+}
diff --git a/javatests/com/google/gerrit/server/events/EventDeserializerTest.java b/javatests/com/google/gerrit/server/events/EventDeserializerTest.java
index e0223e4..97f6e4e 100644
--- a/javatests/com/google/gerrit/server/events/EventDeserializerTest.java
+++ b/javatests/com/google/gerrit/server/events/EventDeserializerTest.java
@@ -22,6 +22,8 @@
 import com.google.gerrit.entities.BranchNameKey;
 import com.google.gerrit.entities.Change;
 import com.google.gerrit.entities.Project;
+import com.google.gerrit.server.config.AllProjectsName;
+import com.google.gerrit.server.config.AllUsersName;
 import com.google.gerrit.server.data.AccountAttribute;
 import com.google.gerrit.server.data.ChangeAttribute;
 import com.google.gerrit.server.data.RefUpdateAttribute;
@@ -240,6 +242,31 @@
     assertSameChangeEvent(e, orig);
   }
 
+  @Test
+  public void shouldSerializeAllProjectsToString() {
+    String allProjectsString = "foobar";
+    AllProjectsName allProjectsNameKey = new AllProjectsName(allProjectsString);
+
+    assertThat(gson.toJson(allProjectsNameKey))
+        .isEqualTo(String.format("\"%s\"", allProjectsString));
+  }
+
+  @Test
+  public void shouldSerializeAllUsersToString() {
+    String allUsersString = "foobar";
+    AllUsersName allUsersNameKey = new AllUsersName(allUsersString);
+
+    assertThat(gson.toJson(allUsersNameKey)).isEqualTo(String.format("\"%s\"", allUsersString));
+  }
+
+  @Test
+  public void shouldSerializeProjectNameKeyToString() {
+    String projectString = "foobar";
+    Project.NameKey projectNameKey = Project.nameKey(projectString);
+
+    assertThat(gson.toJson(projectNameKey)).isEqualTo(String.format("\"%s\"", projectString));
+  }
+
   private <T> Supplier<T> createSupplier(T value) {
     return Suppliers.memoize(() -> value);
   }
diff --git a/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section.ts b/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section.ts
index aa28f04..a793d13 100644
--- a/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section.ts
+++ b/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section.ts
@@ -38,6 +38,7 @@
   CapabilityInfoMap,
   GitRef,
   LabelNameToLabelTypeInfoMap,
+  RepoName,
 } from '../../../types/common';
 import {PolymerDomRepeatEvent} from '../../../types/types';
 import {fireEvent} from '../../../utils/event-util';
@@ -74,6 +75,9 @@
     return htmlTemplate;
   }
 
+  @property({type: String})
+  repo?: RepoName;
+
   @property({type: Object})
   capabilities?: CapabilityInfoMap;
 
diff --git a/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section_html.ts b/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section_html.ts
index 46968eb..2821632 100644
--- a/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section_html.ts
+++ b/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section_html.ts
@@ -120,6 +120,7 @@
             section="[[section.id]]"
             editing="[[editing]]"
             groups="[[groups]]"
+            repo="[[repo]]"
             on-added-permission-removed="_handleAddedPermissionRemoved"
           >
           </gr-permission>
diff --git a/polygerrit-ui/app/elements/admin/gr-permission/gr-permission.ts b/polygerrit-ui/app/elements/admin/gr-permission/gr-permission.ts
index 6f11a33..4b17476 100644
--- a/polygerrit-ui/app/elements/admin/gr-permission/gr-permission.ts
+++ b/polygerrit-ui/app/elements/admin/gr-permission/gr-permission.ts
@@ -38,6 +38,7 @@
   ProjectAccessGroups,
   GroupId,
   GitRef,
+  RepoName,
 } from '../../../types/common';
 import {
   AutocompleteQuery,
@@ -97,6 +98,9 @@
     return htmlTemplate;
   }
 
+  @property({type: String})
+  repo?: RepoName;
+
   @property({type: Object})
   labels?: LabelNameToLabelTypeInfoMap;
 
@@ -320,7 +324,11 @@
 
   _getGroupSuggestions(): Promise<AutocompleteSuggestion[]> {
     return this.restApiService
-      .getSuggestedGroups(this._groupFilter || '', MAX_AUTOCOMPLETE_RESULTS)
+      .getSuggestedGroups(
+        this._groupFilter || '',
+        this.repo,
+        MAX_AUTOCOMPLETE_RESULTS
+      )
       .then(response => {
         const groups: GroupSuggestion[] = [];
         for (const [name, value] of Object.entries(response ?? {})) {
diff --git a/polygerrit-ui/app/elements/admin/gr-plugin-config-array-editor/gr-plugin-config-array-editor.ts b/polygerrit-ui/app/elements/admin/gr-plugin-config-array-editor/gr-plugin-config-array-editor.ts
index 248a0e3..0a0259a 100644
--- a/polygerrit-ui/app/elements/admin/gr-plugin-config-array-editor/gr-plugin-config-array-editor.ts
+++ b/polygerrit-ui/app/elements/admin/gr-plugin-config-array-editor/gr-plugin-config-array-editor.ts
@@ -23,7 +23,6 @@
 import {PolymerElement} from '@polymer/polymer/polymer-element';
 import {htmlTemplate} from './gr-plugin-config-array-editor_html';
 import {property, customElement} from '@polymer/decorators';
-import {PolymerDeepPropertyChange} from '@polymer/polymer/interfaces';
 import {
   PluginConfigOptionsChangedEventDetail,
   ArrayPluginOption,
@@ -55,19 +54,8 @@
   @property({type: Object})
   pluginOption!: ArrayPluginOption;
 
-  @property({type: Boolean, computed: '_computeDisabled(pluginOption.*)'})
-  disabled?: boolean;
-
-  _computeDisabled(
-    record: PolymerDeepPropertyChange<ArrayPluginOption, ArrayPluginOption>
-  ) {
-    return !(
-      record &&
-      record.base &&
-      record.base.info &&
-      record.base.info.editable
-    );
-  }
+  @property({type: Boolean, reflectToAttribute: true})
+  disabled = false;
 
   _handleAddTap(e: MouseEvent) {
     e.preventDefault();
diff --git a/polygerrit-ui/app/elements/admin/gr-plugin-config-array-editor/gr-plugin-config-array-editor_html.ts b/polygerrit-ui/app/elements/admin/gr-plugin-config-array-editor/gr-plugin-config-array-editor_html.ts
index c96b86c..7709198 100644
--- a/polygerrit-ui/app/elements/admin/gr-plugin-config-array-editor/gr-plugin-config-array-editor_html.ts
+++ b/polygerrit-ui/app/elements/admin/gr-plugin-config-array-editor/gr-plugin-config-array-editor_html.ts
@@ -85,6 +85,7 @@
           id="input"
           on-keydown="_handleInputKeydown"
           bind-value="{{_newValue}}"
+          disabled$="[[disabled]]"
         />
       </iron-input>
       <gr-button
diff --git a/polygerrit-ui/app/elements/admin/gr-plugin-config-array-editor/gr-plugin-config-array-editor_test.js b/polygerrit-ui/app/elements/admin/gr-plugin-config-array-editor/gr-plugin-config-array-editor_test.js
index dfc191f..326ff44 100644
--- a/polygerrit-ui/app/elements/admin/gr-plugin-config-array-editor/gr-plugin-config-array-editor_test.js
+++ b/polygerrit-ui/app/elements/admin/gr-plugin-config-array-editor/gr-plugin-config-array-editor_test.js
@@ -42,16 +42,6 @@
     assert.equal(element._computeShowInputRow(false), '');
   });
 
-  test('_computeDisabled', () => {
-    assert.isTrue(element._computeDisabled({}));
-    assert.isTrue(element._computeDisabled({base: {}}));
-    assert.isTrue(element._computeDisabled({base: {info: {}}}));
-    assert.isTrue(
-        element._computeDisabled({base: {info: {editable: false}}}));
-    assert.isFalse(
-        element._computeDisabled({base: {info: {editable: true}}}));
-  });
-
   suite('adding', () => {
     setup(() => {
       dispatchStub = sinon.stub(element, '_dispatchChanged');
@@ -60,11 +50,13 @@
     test('with enter', () => {
       element._newValue = '';
       MockInteractions.pressAndReleaseKeyOn(element.$.input, 13); // Enter
+      assert.isFalse(element.$.input.hasAttribute('disabled'));
       flush();
 
       assert.isFalse(dispatchStub.called);
       element._newValue = 'test';
       MockInteractions.pressAndReleaseKeyOn(element.$.input, 13); // Enter
+      assert.isFalse(element.$.input.hasAttribute('disabled'));
       flush();
 
       assert.isTrue(dispatchStub.called);
@@ -91,6 +83,7 @@
   test('deleting', () => {
     dispatchStub = sinon.stub(element, '_dispatchChanged');
     element.pluginOption = {info: {values: ['test', 'test2']}};
+    element.disabled = true;
     flush();
 
     const rows = getAll('.existingItems .row');
@@ -101,7 +94,7 @@
     flush();
 
     assert.isFalse(dispatchStub.called);
-    element.pluginOption.info.editable = true;
+    element.disabled = false;
     element.notifyPath('pluginOption.info.editable');
     flush();
 
diff --git a/polygerrit-ui/app/elements/admin/gr-repo-access/gr-repo-access_html.ts b/polygerrit-ui/app/elements/admin/gr-repo-access/gr-repo-access_html.ts
index c9af6f0..1eba2e7 100644
--- a/polygerrit-ui/app/elements/admin/gr-repo-access/gr-repo-access_html.ts
+++ b/polygerrit-ui/app/elements/admin/gr-repo-access/gr-repo-access_html.ts
@@ -112,6 +112,7 @@
           editing="[[_editing]]"
           owner-of="[[_ownerOf]]"
           groups="[[_groups]]"
+          repo="[[repo]]"
           on-added-section-removed="_handleAddedSectionRemoved"
         ></gr-access-section>
       </template>
diff --git a/polygerrit-ui/app/elements/admin/gr-repo-plugin-config/gr-repo-plugin-config.ts b/polygerrit-ui/app/elements/admin/gr-repo-plugin-config/gr-repo-plugin-config.ts
index 07eef31..ef35f63 100644
--- a/polygerrit-ui/app/elements/admin/gr-repo-plugin-config/gr-repo-plugin-config.ts
+++ b/polygerrit-ui/app/elements/admin/gr-repo-plugin-config/gr-repo-plugin-config.ts
@@ -80,6 +80,9 @@
   })
   _pluginConfigOptions!: PluginOption[]; // _computePluginConfigOptions never returns null
 
+  @property({type: Boolean, reflectToAttribute: true})
+  disabled = false;
+
   _computePluginConfigOptions(
     dataRecord: PolymerDeepPropertyChange<PluginData, PluginData>
   ): PluginOption[] {
@@ -113,8 +116,8 @@
     );
   }
 
-  _computeDisabled(editable: boolean) {
-    return !editable;
+  _computeDisabled(disabled: boolean, editable: boolean) {
+    return disabled || !editable;
   }
 
   _computeChecked(value = 'false') {
diff --git a/polygerrit-ui/app/elements/admin/gr-repo-plugin-config/gr-repo-plugin-config_html.ts b/polygerrit-ui/app/elements/admin/gr-repo-plugin-config/gr-repo-plugin-config_html.ts
index 1a7c2a0..2920cdf 100644
--- a/polygerrit-ui/app/elements/admin/gr-repo-plugin-config/gr-repo-plugin-config_html.ts
+++ b/polygerrit-ui/app/elements/admin/gr-repo-plugin-config/gr-repo-plugin-config_html.ts
@@ -55,6 +55,7 @@
               <gr-plugin-config-array-editor
                 on-plugin-config-option-changed="_handleArrayChange"
                 plugin-option="[[option]]"
+                disabled$="[[_computeDisabled(disabled, option.info.editable)]]"
               ></gr-plugin-config-array-editor>
             </template>
             <template is="dom-if" if="[[_isBoolean(option.info.type)]]">
@@ -62,7 +63,7 @@
                 checked="[[_computeChecked(option.info.value)]]"
                 on-change="_handleBooleanChange"
                 data-option-key$="[[option._key]]"
-                disabled$="[[_computeDisabled(option.info.editable)]]"
+                disabled$="[[_computeDisabled(disabled, option.info.editable)]]"
                 on-click="_onTapPluginBoolean"
               ></paper-toggle-button>
             </template>
@@ -73,7 +74,7 @@
               >
                 <select
                   data-option-key$="[[option._key]]"
-                  disabled$="[[_computeDisabled(option.info.editable)]]"
+                  disabled$="[[_computeDisabled(disabled, option.info.editable)]]"
                 >
                   <template
                     is="dom-repeat"
@@ -90,14 +91,14 @@
                 bind-value="[[option.info.value]]"
                 on-input="_handleStringChange"
                 data-option-key$="[[option._key]]"
-                disabled$="[[_computeDisabled(option.info.editable)]]"
+                disabled$="[[_computeDisabled(disabled, option.info.editable)]]"
               >
                 <input
                   is="iron-input"
                   value="[[option.info.value]]"
                   on-input="_handleStringChange"
                   data-option-key$="[[option._key]]"
-                  disabled$="[[_computeDisabled(option.info.editable)]]"
+                  disabled$="[[_computeDisabled(disabled, option.info.editable)]]"
                 />
               </iron-input>
             </template>
diff --git a/polygerrit-ui/app/elements/admin/gr-repo-plugin-config/gr-repo-plugin-config_test.js b/polygerrit-ui/app/elements/admin/gr-repo-plugin-config/gr-repo-plugin-config_test.js
index 28ef2f8..a5c7dfe 100644
--- a/polygerrit-ui/app/elements/admin/gr-repo-plugin-config/gr-repo-plugin-config_test.js
+++ b/polygerrit-ui/app/elements/admin/gr-repo-plugin-config/gr-repo-plugin-config_test.js
@@ -39,10 +39,11 @@
   });
 
   test('_computeDisabled', () => {
-    assert.isFalse(element._computeDisabled(true));
-    assert.isTrue(element._computeDisabled(undefined));
-    assert.isTrue(element._computeDisabled(null));
-    assert.isTrue(element._computeDisabled(false));
+    assert.isFalse(element._computeDisabled(false, true));
+    assert.isTrue(element._computeDisabled(false, undefined));
+    assert.isTrue(element._computeDisabled(false, null));
+    assert.isTrue(element._computeDisabled(false, false));
+    assert.isTrue(element._computeDisabled(true, true));
   });
 
   test('_handleChange', () => {
diff --git a/polygerrit-ui/app/elements/admin/gr-repo/gr-repo_html.ts b/polygerrit-ui/app/elements/admin/gr-repo/gr-repo_html.ts
index b88eeaf..8db498a 100644
--- a/polygerrit-ui/app/elements/admin/gr-repo/gr-repo_html.ts
+++ b/polygerrit-ui/app/elements/admin/gr-repo/gr-repo_html.ts
@@ -418,6 +418,7 @@
             <template is="dom-repeat" items="[[_pluginData]]" as="data">
               <gr-repo-plugin-config
                 plugin-data="[[data]]"
+                disabled$="[[_readOnly]]"
               ></gr-repo-plugin-config>
             </template>
           </div>
diff --git a/polygerrit-ui/app/elements/core/gr-smart-search/gr-smart-search.ts b/polygerrit-ui/app/elements/core/gr-smart-search/gr-smart-search.ts
index aa7e2e0..3dfe1eb 100644
--- a/polygerrit-ui/app/elements/core/gr-smart-search/gr-smart-search.ts
+++ b/polygerrit-ui/app/elements/core/gr-smart-search/gr-smart-search.ts
@@ -117,7 +117,7 @@
       return Promise.resolve([]);
     }
     return this.restApiService
-      .getSuggestedGroups(expression, MAX_AUTOCOMPLETE_RESULTS)
+      .getSuggestedGroups(expression, undefined, MAX_AUTOCOMPLETE_RESULTS)
       .then(groups => {
         if (!groups) {
           return [];
diff --git a/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.ts b/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.ts
index 2067a6b..4a47db6 100644
--- a/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.ts
+++ b/polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.ts
@@ -240,6 +240,7 @@
   [paramName: string]: string | undefined | null | number;
   s: string;
   n?: number;
+  p?: string;
 }
 
 interface QuerySuggestedReviewersParams {
@@ -1592,12 +1593,16 @@
 
   getSuggestedGroups(
     inputVal: string,
+    project?: RepoName,
     n?: number
   ): Promise<GroupNameToGroupInfoMap | undefined> {
     const params: QueryGroupsParams = {s: inputVal};
     if (n) {
       params.n = n;
     }
+    if (project) {
+      params.p = encodeURIComponent(project);
+    }
     return this._restApiHelper.fetchJSON({
       url: '/groups/',
       params,
diff --git a/polygerrit-ui/app/elements/shared/gr-tooltip/gr-tooltip_test.js b/polygerrit-ui/app/elements/shared/gr-tooltip/gr-tooltip_test.js
index b5f068c..65a442b 100644
--- a/polygerrit-ui/app/elements/shared/gr-tooltip/gr-tooltip_test.js
+++ b/polygerrit-ui/app/elements/shared/gr-tooltip/gr-tooltip_test.js
@@ -26,8 +26,9 @@
 
 suite('gr-tooltip tests', () => {
   let element;
-  setup(() => {
+  setup(async () => {
     element = basicFixture.instantiate();
+    await flush();
   });
 
   test('max-width is respected if set', () => {
diff --git a/polygerrit-ui/app/mixins/keyboard-shortcut-mixin/keyboard-shortcut-mixin.ts b/polygerrit-ui/app/mixins/keyboard-shortcut-mixin/keyboard-shortcut-mixin.ts
index 58e50d3..7b740fb 100644
--- a/polygerrit-ui/app/mixins/keyboard-shortcut-mixin/keyboard-shortcut-mixin.ts
+++ b/polygerrit-ui/app/mixins/keyboard-shortcut-mixin/keyboard-shortcut-mixin.ts
@@ -843,9 +843,10 @@
         ) {
           return true;
         }
-        for (let i = 0; e.path && i < e.path.length; i++) {
+        const path = e.composedPath();
+        for (let i = 0; path && i < path.length; i++) {
           // TODO(TS): narrow this down to Element from EventTarget first
-          if ((e.path[i] as Element).tagName === 'GR-OVERLAY') {
+          if ((path[i] as Element).tagName === 'GR-OVERLAY') {
             return true;
           }
         }
diff --git a/polygerrit-ui/app/services/gr-rest-api/gr-rest-api.ts b/polygerrit-ui/app/services/gr-rest-api/gr-rest-api.ts
index d92fe7c..581f10b 100644
--- a/polygerrit-ui/app/services/gr-rest-api/gr-rest-api.ts
+++ b/polygerrit-ui/app/services/gr-rest-api/gr-rest-api.ts
@@ -180,6 +180,7 @@
   ): Promise<AccountInfo[] | undefined>;
   getSuggestedGroups(
     input: string,
+    project?: RepoName,
     n?: number
   ): Promise<GroupNameToGroupInfoMap | undefined>;
   executeChangeAction(
diff --git a/resources/com/google/gerrit/httpd/auth/container/LoginRedirect.html b/resources/com/google/gerrit/httpd/auth/container/LoginRedirect.html
index 0567468..54c3661 100644
--- a/resources/com/google/gerrit/httpd/auth/container/LoginRedirect.html
+++ b/resources/com/google/gerrit/httpd/auth/container/LoginRedirect.html
@@ -4,6 +4,12 @@
     <title>Gerrit Code Review</title>
     <script type="text/javascript">
       var href = window.location.href;
+      var query = "";
+      var q = href.indexOf('?');
+      if (q >= 0) {
+        query = href.substring(q);
+        href = href.substring(0,q);
+      }
       var p = href.indexOf('#');
       var token;
       if (p >= 0) {
@@ -12,7 +18,7 @@
       } else {
         token = '';
       }
-      window.location.replace(href + 'login/' + token);
+      window.location.replace(href + 'login/' + token + query);
     </script>
   </head>
   <body>
diff --git a/tools/bzl/license-map.py b/tools/bzl/license-map.py
index 555aa17..3e4fc92 100644
--- a/tools/bzl/license-map.py
+++ b/tools/bzl/license-map.py
@@ -24,7 +24,7 @@
 
 def read_file(filename):
     "Reads file and returns its content"
-    with open(filename) as fd:
+    with open(filename, encoding='utf-8') as fd:
         return fd.read()
 
 # List of files in package to which license is applied.
@@ -56,6 +56,8 @@
 LicenseMapItem = namedtuple("LicenseMapItem",
                             ["name", "safename", "packages", "license_text"])
 
+def print_utf8(str=""):
+  stdout.buffer.write((str + "\n").encode('utf-8'))
 
 def load_xmls(xml_filenames):
     """Load xml files produced by bazel query
@@ -134,7 +136,7 @@
 
     if args.asciidoctor:
         # We don't want any blank line before "= Gerrit Code Review - Licenses"
-        print("""= Gerrit Code Review - Licenses
+        print_utf8("""= Gerrit Code Review - Licenses
 
 // DO NOT EDIT - GENERATED AUTOMATICALLY.
 
@@ -178,10 +180,10 @@
     for data in xml_data + json_map_data:
         name = data.name
         safename = data.safename
-        print()
-        print("[[%s]]" % safename)
-        print(name)
-        print()
+        print_utf8()
+        print_utf8("[[%s]]" % safename)
+        print_utf8(name)
+        print_utf8()
         for p in data.packages:
             package_notice = ""
             if p.licensed_files.kind == "OnlySpecificFiles":
@@ -189,20 +191,20 @@
             elif p.licensed_files.kind == "AllFilesExceptSpecific":
                 package_notice = " - except the following file(s):"
 
-            print("* " + get_package_display_name(p) + package_notice)
+            print_utf8("* " + get_package_display_name(p) + package_notice)
             for file in p.licensed_files.files:
-                print("** " + file)
-        print()
-        print("[[%s_license]]" % safename)
-        print("----")
+                print_utf8("** " + file)
+        print_utf8()
+        print_utf8("[[%s_license]]" % safename)
+        print_utf8("----")
         license_text = data.license_text
-        print(data.license_text.rstrip("\r\n"))
-        print()
-        print("----")
-        print()
+        print_utf8(data.license_text.rstrip("\r\n"))
+        print_utf8()
+        print_utf8("----")
+        print_utf8()
 
     if args.asciidoctor:
-        print("""
+        print_utf8("""
 GERRIT
 ------
 Part of link:index.html[Gerrit Code Review]
@@ -219,7 +221,7 @@
     """
     result = []
     for json_map in json_filenames:
-        with open(json_map, 'r') as f:
+        with open(json_map, 'r', encoding='utf-8') as f:
             licenses_list = json.load(f)
         for license_id, license in licenses_list.items():
             name = license["licenseName"]