diff --git a/java/com/google/gerrit/httpd/restapi/RestApiServlet.java b/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
index 0535397..9c6637b 100644
--- a/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
+++ b/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
@@ -1670,18 +1670,37 @@
     if (!res.isCommitted()) {
       res.reset();
       traceContext.getTraceId().ifPresent(traceId -> res.addHeader(X_GERRIT_TRACE, traceId));
-      StringBuilder msg = new StringBuilder("Internal server error");
       ImmutableList<String> userMessages =
           globals.exceptionHooks.stream()
               .map(h -> h.getUserMessage(err))
               .filter(Optional::isPresent)
               .map(Optional::get)
               .collect(toImmutableList());
+
+      Optional<Integer> statusCode =
+          globals.exceptionHooks.stream()
+              .map(h -> h.getStatusCode(err))
+              .filter(Optional::isPresent)
+              .map(Optional::get)
+              .findFirst();
+      if (statusCode.isPresent() && statusCode.get() < 400) {
+        StringBuilder msg = new StringBuilder();
+        if (userMessages.size() == 1) {
+          msg.append(userMessages.get(0));
+        } else {
+          userMessages.forEach(m -> msg.append("\n* ").append(m));
+        }
+
+        res.setStatus(statusCode.get());
+        logger.atFinest().withCause(err).log("REST call finished: %d", statusCode);
+        return replyText(req, res, true, msg.toString());
+      }
+
+      StringBuilder msg = new StringBuilder("Internal server error");
       if (!userMessages.isEmpty()) {
-        msg.append("\n");
         userMessages.forEach(m -> msg.append("\n* ").append(m));
       }
-      return replyError(req, res, SC_INTERNAL_SERVER_ERROR, msg.toString(), err);
+      return replyError(req, res, statusCode.orElse(SC_INTERNAL_SERVER_ERROR), msg.toString(), err);
     }
     return 0;
   }
diff --git a/java/com/google/gerrit/server/ExceptionHook.java b/java/com/google/gerrit/server/ExceptionHook.java
index db44b4b..a2bade0 100644
--- a/java/com/google/gerrit/server/ExceptionHook.java
+++ b/java/com/google/gerrit/server/ExceptionHook.java
@@ -55,7 +55,9 @@
   }
 
   /**
-   * Returns an error message that should be returned to the user.
+   * Returns a message that should be returned to the user.
+   *
+   * <p>This message is included into the HTTP response that is sent to the user.
    *
    * @param throwable throwable that was thrown while executing an operation
    * @return error message that should be returned to the user, {@link Optional#empty()} if no
@@ -64,4 +66,25 @@
   default Optional<String> getUserMessage(Throwable throwable) {
     return Optional.empty();
   }
+
+  /**
+   * Returns the HTTP status code that should be returned to the user.
+   *
+   * <p>If no value is returned ({@link Optional#empty()}) the HTTP status code defaults to {@code
+   * 500 Internal Server Error}.
+   *
+   * <p>{@link #getUserMessage(Throwable)} allows to define which message should be included into
+   * the body of the HTTP response.
+   *
+   * <p>Implementors may use this method to change the status code for certain exceptions (e.g.
+   * using this method it would be possible to return {@code 409 Conflict} for {@link
+   * com.google.gerrit.git.LockFailureException}s instead of {@code 500 Internal Server Error}).
+   *
+   * @param throwable throwable that was thrown while executing an operation
+   * @return HTTP status code that should be returned to the user, {@link Optional#empty()} if the
+   *     exception should result in {@code 500 Internal Server Error}
+   */
+  default Optional<Integer> getStatusCode(Throwable throwable) {
+    return Optional.empty();
+  }
 }