diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/Action.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/Action.java
index d232382..7e80fd9 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/findowners/Action.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/Action.java
@@ -32,6 +32,7 @@
 import com.google.gerrit.server.change.RevisionResource;
 import com.google.gerrit.server.config.PluginConfigFactory;
 import com.google.gerrit.server.git.GitRepositoryManager;
+import com.google.gerrit.server.project.ProjectCache;
 import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gwtorm.server.OrmException;
 import com.google.gwtorm.server.SchemaFactory;
@@ -60,6 +61,7 @@
   private GitRepositoryManager repoManager;
   private Provider<CurrentUser> userProvider;
   private SchemaFactory<ReviewDb> reviewDbProvider;
+  private ProjectCache projectCache;
 
   static class Parameters {
     Boolean debug; // REST API "debug" parameter, or null
@@ -75,13 +77,15 @@
       ChangeData.Factory changeDataFactory,
       AccountCache accountCache,
       Emails emails,
-      GitRepositoryManager repoManager) {
+      GitRepositoryManager repoManager,
+      ProjectCache projectCache) {
     this.userProvider = userProvider;
     this.reviewDbProvider = reviewDbProvider;
     this.changeDataFactory = changeDataFactory;
     this.accountCache = accountCache;
     this.emails = emails;
     this.repoManager = repoManager;
+    this.projectCache = projectCache;
     Config.setVariables(pluginName, configFactory);
     Cache.getInstance(); // Create a single Cache.
   }
@@ -171,7 +175,15 @@
       Repository repository, Parameters params, ChangeData changeData)
       throws OrmException, BadRequestException, IOException {
     int patchset = getValidPatchsetNum(changeData, params.patchset);
-    OwnersDb db = Cache.getInstance().get(accountCache, emails, repository, changeData, patchset);
+    OwnersDb db =
+        Cache.getInstance()
+            .get(
+                projectCache.get(changeData.project()),
+                accountCache,
+                emails,
+                repository,
+                changeData,
+                patchset);
     Collection<String> changedFiles = changeData.currentFilePaths();
     Map<String, Set<String>> file2Owners = db.findOwners(changedFiles);
 
@@ -219,7 +231,14 @@
       if (needFindOwners && !Config.getAlwaysShowButton()) {
         needFindOwners = false; // Show button only if some owner is found.
         try (Repository repo = repoManager.openRepository(change.getProject())) {
-          OwnersDb db = Cache.getInstance().get(accountCache, emails, repo, changeData);
+          OwnersDb db =
+              Cache.getInstance()
+                  .get(
+                      projectCache.get(resource.getProject()),
+                      accountCache,
+                      emails,
+                      repo,
+                      changeData);
           log.trace("getDescription db key = " + db.key);
           needFindOwners = db.getNumOwners() > 0;
         }
diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/Cache.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/Cache.java
index aa43896..3f48166 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/findowners/Cache.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/Cache.java
@@ -17,9 +17,9 @@
 import static java.util.concurrent.TimeUnit.SECONDS;
 
 import com.google.common.cache.CacheBuilder;
-import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.account.AccountCache;
 import com.google.gerrit.server.account.Emails;
+import com.google.gerrit.server.project.ProjectState;
 import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gwtorm.server.OrmException;
 import java.io.IOException;
@@ -88,48 +88,59 @@
   }
 
   /** Returns a cached or new OwnersDb, for the current patchset. */
-  OwnersDb get(AccountCache accountCache, Emails emails, Repository repo, ChangeData changeData)
+  OwnersDb get(
+      ProjectState projectState,
+      AccountCache accountCache,
+      Emails emails,
+      Repository repo,
+      ChangeData changeData)
       throws OrmException, IOException {
-    return get(accountCache, emails, repo, changeData, changeData.currentPatchSet().getId().get());
+    return get(
+        projectState,
+        accountCache,
+        emails,
+        repo,
+        changeData,
+        changeData.currentPatchSet().getId().get());
   }
 
   /** Returns a cached or new OwnersDb, for the specified patchset. */
   OwnersDb get(
+      ProjectState projectState,
       AccountCache accountCache,
       Emails emails,
       Repository repository,
       ChangeData changeData,
       int patchset)
       throws OrmException, IOException {
-    Project.NameKey project = changeData.change().getProject();
     String branch = changeData.change().getDest().get();
     String dbKey = Cache.makeKey(changeData.getId().get(), patchset, branch);
     // TODO: get changed files of the given patchset?
     return get(
+        projectState,
         accountCache,
         emails,
         dbKey,
         repository,
         changeData,
-        project,
         branch,
         changeData.currentFilePaths());
   }
 
   /** Returns a cached or new OwnersDb, for the specified branch and changed files. */
   OwnersDb get(
+      ProjectState projectState,
       AccountCache accountCache,
       Emails emails,
       String key,
       Repository repository,
       ChangeData changeData,
-      Project.NameKey project,
       String branch,
       Collection<String> files) {
     if (dbCache == null) { // Do not cache OwnersDb
       log.trace("Create new OwnersDb, key=" + key);
       return new OwnersDb(
-          accountCache, emails, key, repository, changeData, project, branch, files);
+          projectState, accountCache, emails, key, repository, changeData, branch, files);
     }
     try {
       log.trace("Get from cash " + dbCache + ", key=" + key + ", cache size=" + dbCache.size());
@@ -140,13 +151,13 @@
             public OwnersDb call() {
               log.trace("Create new OwnersDb, key=" + key);
               return new OwnersDb(
-                  accountCache, emails, key, repository, changeData, project, branch, files);
+                  projectState, accountCache, emails, key, repository, changeData, branch, files);
             }
           });
     } catch (ExecutionException e) {
       log.error("Cache.get has exception for " + Config.getChangeId(changeData), e);
       return new OwnersDb(
-          accountCache, emails, key, repository, changeData, project, branch, files);
+          projectState, accountCache, emails, key, repository, changeData, branch, files);
     }
   }
 
diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/Checker.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/Checker.java
index cb206b8..03225df 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/findowners/Checker.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/Checker.java
@@ -18,6 +18,7 @@
 import com.google.gerrit.reviewdb.client.PatchSetApproval;
 import com.google.gerrit.server.account.AccountCache;
 import com.google.gerrit.server.account.Emails;
+import com.google.gerrit.server.project.ProjectState;
 import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gerrit.server.rules.StoredValues;
 import com.google.gwtorm.server.OrmException;
@@ -104,10 +105,12 @@
     ChangeData changeData = null;
     try {
       changeData = StoredValues.CHANGE_DATA.get(engine);
+      ProjectState projectState = StoredValues.PROJECT_STATE.get(engine);
       AccountCache accountCache = StoredValues.ACCOUNT_CACHE.get(engine);
       Emails emails = StoredValues.EMAILS.get(engine);
       Repository repository = StoredValues.REPOSITORY.get(engine);
-      return new Checker(repository, changeData, minVoteLevel).findApproval(accountCache, emails);
+      return new Checker(repository, changeData, minVoteLevel)
+          .findApproval(projectState, accountCache, emails);
     } catch (OrmException | IOException e) {
       log.error("Exception for " + Config.getChangeId(changeData), e);
       return 0; // owner approval may or may not be required.
@@ -130,13 +133,15 @@
     return (status == Status.ABANDONED || status == Status.MERGED);
   }
 
-  int findApproval(AccountCache accountCache, Emails emails) throws OrmException, IOException {
+  int findApproval(ProjectState projectState, AccountCache accountCache, Emails emails)
+      throws OrmException, IOException {
     if (isExemptFromOwnerApproval(changeData)) {
       return 0;
     }
     // One update to a Gerrit change can call submit_rule or submit_filter
     // many times. So this function should use cached values.
-    OwnersDb db = Cache.getInstance().get(accountCache, emails, repository, changeData);
+    OwnersDb db =
+        Cache.getInstance().get(projectState, accountCache, emails, repository, changeData);
     if (db.getNumOwners() <= 0) {
       return 0;
     }
diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/Config.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/Config.java
index e450dfb..e69275d 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/findowners/Config.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/Config.java
@@ -19,6 +19,7 @@
 import com.google.gerrit.server.config.PluginConfig;
 import com.google.gerrit.server.config.PluginConfigFactory;
 import com.google.gerrit.server.project.NoSuchProjectException;
+import com.google.gerrit.server.project.ProjectState;
 import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gwtorm.server.OrmException;
 import org.slf4j.Logger;
@@ -91,29 +92,31 @@
     return data == null ? "(unknown change)" : ("change c/" + data.getId().get());
   }
 
-  static String getOwnersFileName(Project.NameKey project, ChangeData c) {
-    if (config != null && project != null) {
-      try {
-        String name =
-            config
-                .getFromProjectConfigWithInheritance(project, PLUGIN_NAME)
-                .getString(OWNERS_FILE_NAME, OWNERS);
-        if (name.trim().equals("")) {
-          log.error(
-              "Project "
-                  + project
-                  + " has wrong "
-                  + OWNERS_FILE_NAME
-                  + ": \""
-                  + name
-                  + "\" for "
-                  + getChangeId(c));
-          return OWNERS;
-        }
-        return name;
-      } catch (NoSuchProjectException e) {
-        log.error("Cannot find project " + project + " for " + getChangeId(c), e);
+  static String getDefaultOwnersFileName() {
+    return OWNERS;
+  }
+
+  static String getOwnersFileName(ProjectState projectState, ChangeData c) {
+    if (projectState == null) {
+      log.error("Null projectState for change " + getChangeId(c));
+    } else if (config != null) {
+      String name =
+          config
+              .getFromProjectConfigWithInheritance(projectState, PLUGIN_NAME)
+              .getString(OWNERS_FILE_NAME, OWNERS);
+      if (name.trim().equals("")) {
+        log.error(
+            "Project "
+                + projectState.getProject()
+                + " has wrong "
+                + OWNERS_FILE_NAME
+                + ": \""
+                + name
+                + "\" for "
+                + getChangeId(c));
+        return OWNERS;
       }
+      return name;
     }
     return OWNERS;
   }
diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/GetOwners.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/GetOwners.java
index fd60850..322a3b5 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/findowners/GetOwners.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/GetOwners.java
@@ -25,6 +25,7 @@
 import com.google.gerrit.server.change.ChangeResource;
 import com.google.gerrit.server.config.PluginConfigFactory;
 import com.google.gerrit.server.git.GitRepositoryManager;
+import com.google.gerrit.server.project.ProjectCache;
 import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gwtorm.server.OrmException;
 import com.google.gwtorm.server.SchemaFactory;
@@ -58,7 +59,8 @@
       ChangeData.Factory dataFactory,
       AccountCache accountCache,
       Emails emails,
-      GitRepositoryManager repoManager) {
+      GitRepositoryManager repoManager,
+      ProjectCache projectCache) {
     this.action =
         new Action(
             pluginName,
@@ -68,7 +70,8 @@
             dataFactory,
             accountCache,
             emails,
-            repoManager);
+            repoManager,
+            projectCache);
   }
 
   @Override
diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnersDb.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnersDb.java
index 2c595b2..9bb11a1 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnersDb.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnersDb.java
@@ -18,9 +18,9 @@
 
 import com.google.common.collect.Multimap;
 import com.google.gerrit.reviewdb.client.Account;
-import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.account.AccountCache;
 import com.google.gerrit.server.account.Emails;
+import com.google.gerrit.server.project.ProjectState;
 import com.google.gerrit.server.query.change.ChangeData;
 import java.nio.file.FileSystem;
 import java.nio.file.FileSystems;
@@ -63,19 +63,19 @@
   OwnersDb() {}
 
   OwnersDb(
+      ProjectState projectState,
       AccountCache accountCache,
       Emails emails,
       String key,
       Repository repository,
       ChangeData changeData,
-      Project.NameKey project,
       String branch,
       Collection<String> files) {
     this.accountCache = accountCache;
     this.emails = emails;
     this.key = key;
     preferredEmails.put("*", "*");
-    String ownersFileName = Config.getOwnersFileName(project, changeData);
+    String ownersFileName = Config.getOwnersFileName(projectState, changeData);
     // Some hacked CL could have a target branch that is not created yet.
     ObjectId id = getBranchId(repository, branch, changeData);
     revision = "";
diff --git a/src/test/java/com/googlesource/gerrit/plugins/findowners/FindOwnersIT.java b/src/test/java/com/googlesource/gerrit/plugins/findowners/FindOwnersIT.java
index 160d5fa..6874245 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/findowners/FindOwnersIT.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/findowners/FindOwnersIT.java
@@ -35,6 +35,7 @@
 import com.google.gerrit.server.account.Emails;
 import com.google.gerrit.server.change.ChangeResource;
 import com.google.gerrit.server.config.PluginConfigFactory;
+import com.google.gerrit.server.project.ProjectCache;
 import com.google.inject.Inject;
 import java.util.Collection;
 import org.eclipse.jgit.lib.ObjectLoader;
@@ -51,6 +52,7 @@
 
   @Inject private Emails emails;
   @Inject private PluginConfigFactory configFactory;
+  @Inject private ProjectCache projectCache;
 
   @Test
   public void getOwnersTest() throws Exception {
@@ -259,9 +261,9 @@
     PushOneCommit.Result cB = createChange("add tB.c", "tB.c", "Hello B!");
 
     // Default owners file name is "OWNERS".
-    assertThat(Config.getOwnersFileName(null, null)).isEqualTo("OWNERS");
-    assertThat(Config.getOwnersFileName(pA, null)).isEqualTo("OWNERS");
-    assertThat(Config.getOwnersFileName(pB, null)).isEqualTo("OWNERS");
+    assertThat(Config.getDefaultOwnersFileName()).isEqualTo("OWNERS");
+    assertThat(Config.getOwnersFileName(projectCache.get(pA), null)).isEqualTo("OWNERS");
+    assertThat(Config.getOwnersFileName(projectCache.get(pB), null)).isEqualTo("OWNERS");
 
     String ownerX = oneOwnerList("x@x");
     String ownerY = oneOwnerList("y@y");
@@ -273,8 +275,9 @@
     setProjectConfig("ownersFileName", "OWNERS.alpha");
     switchProject(pB);
     setProjectConfig("ownersFileName", "OWNERS.beta");
-    assertThat(Config.getOwnersFileName(pA, null)).isEqualTo("OWNERS.alpha");
-    assertThat(Config.getOwnersFileName(pB, null)).isEqualTo("OWNERS.beta");
+
+    assertThat(Config.getOwnersFileName(projectCache.get(pA), null)).isEqualTo("OWNERS.alpha");
+    assertThat(Config.getOwnersFileName(projectCache.get(pB), null)).isEqualTo("OWNERS.beta");
     String ownerA = oneOwnerList("a@a");
     String ownerB = oneOwnerList("b@b");
     assertThat(getOwnersResponse(cA)).contains(ownerA + ", files:[ tA.c ]");
@@ -283,24 +286,24 @@
     // Change back to OWNERS in Project_A
     switchProject(pA);
     setProjectConfig("ownersFileName", "OWNERS");
-    assertThat(Config.getOwnersFileName(pA, null)).isEqualTo("OWNERS");
+    assertThat(Config.getOwnersFileName(projectCache.get(pA), null)).isEqualTo("OWNERS");
     assertThat(getOwnersResponse(cA)).contains(ownerX + ", files:[ tA.c ]");
     assertThat(getOwnersResponse(cB)).contains(ownerB + ", files:[ tB.c ]");
 
     // Change back to OWNERS.alpha in Project_B, but there is no OWNERS.alpha
     switchProject(pB);
     setProjectConfig("ownersFileName", "OWNERS.alpha");
-    assertThat(Config.getOwnersFileName(pB, null)).isEqualTo("OWNERS.alpha");
+    assertThat(Config.getOwnersFileName(projectCache.get(pB), null)).isEqualTo("OWNERS.alpha");
     assertThat(getOwnersResponse(cA)).contains(ownerX + ", files:[ tA.c ]");
     assertThat(getOwnersResponse(cB)).contains("owners:[], files:[ tB.c ]");
 
     // Do not accept empty string or all-white-spaces for ownersFileName.
     setProjectConfig("ownersFileName", "   ");
-    assertThat(Config.getOwnersFileName(pB, null)).isEqualTo("OWNERS");
+    assertThat(Config.getOwnersFileName(projectCache.get(pB), null)).isEqualTo("OWNERS");
     setProjectConfig("ownersFileName", " \t  ");
-    assertThat(Config.getOwnersFileName(pB, null)).isEqualTo("OWNERS");
+    assertThat(Config.getOwnersFileName(projectCache.get(pB), null)).isEqualTo("OWNERS");
     setProjectConfig("ownersFileName", "O");
-    assertThat(Config.getOwnersFileName(pB, null)).isEqualTo("O");
+    assertThat(Config.getOwnersFileName(projectCache.get(pB), null)).isEqualTo("O");
   }
 
   @Test
@@ -327,7 +330,15 @@
     Action.Parameters param = new Action.Parameters();
     Action action =
         new Action(
-            "find-owners", null, null, null, changeDataFactory, accountCache, emails, repoManager);
+            "find-owners",
+            null,
+            null,
+            null,
+            changeDataFactory,
+            accountCache,
+            emails,
+            repoManager,
+            projectCache);
     Response<RestResult> response = action.apply(db, cr, param);
     RestResult result = response.value();
     verifyRestResult(result, 1, 1, changeInfo._number, false);
@@ -436,9 +447,11 @@
   }
 
   private int checkApproval(PushOneCommit.Result r) throws Exception {
-    Repository repo = repoManager.openRepository(r.getChange().project());
+    Project.NameKey project = r.getChange().project();
+    Repository repo = repoManager.openRepository(project);
     Cache cache = Cache.getInstance().init(0, 0);
-    OwnersDb db = cache.get(accountCache, emails, repo, r.getChange(), 1);
+    OwnersDb db =
+        cache.get(projectCache.get(project), accountCache, emails, repo, r.getChange(), 1);
     Checker c = new Checker(repo, r.getChange(), 1);
     return c.findApproval(accountCache, db);
   }