Partially resolved issue #4687 by changing the improper status code for concurrent snapshot executions

CHANGELOG.md

@@ -48,6 +48,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Remote Segment Store Repository setting moved from `index.remote_store.repository` to `index.remote_store.segment.repository` and `cluster.remote_store.repository` to `cluster.remote_store.segment.repository` respectively for Index and Cluster level settings ([#8719](https://github.com/opensearch-project/OpenSearch/pull/8719))
 - [Remote Store] Add support to restore only unassigned shards of an index ([#8792](https://github.com/opensearch-project/OpenSearch/pull/8792))
 - Replace the deprecated IndexReader APIs with new storedFields() & termVectors() ([#7792](https://github.com/opensearch-project/OpenSearch/pull/7792))
+- Return 409 Conflict HTTP status instead of 500 on failure to concurrently execute snapshots ([#5855](https://github.com/opensearch-project/OpenSearch/pull/5855))
 
 ### Deprecated
 

server/src/main/java/org/opensearch/snapshots/ConcurrentSnapshotExecutionException.java

@@ -58,6 +58,6 @@ public ConcurrentSnapshotExecutionException(StreamInput in) throws IOException {
 
     @Override
     public RestStatus status() {
-        return RestStatus.SERVICE_UNAVAILABLE;
+        return RestStatus.CONFLICT;
     }
 }

server/src/test/java/org/opensearch/OpenSearchExceptionTests.java

@@ -71,6 +71,7 @@
 import org.opensearch.search.SearchParseException;
 import org.opensearch.search.SearchShardTarget;
 import org.opensearch.search.internal.ShardSearchContextId;
+import org.opensearch.snapshots.ConcurrentSnapshotExecutionException;
 import org.opensearch.test.OpenSearchTestCase;
 import org.opensearch.transport.RemoteTransportException;
 
@@ -119,6 +120,9 @@ public void testStatus() {
 
         exception = new RemoteTransportException("test", new IllegalStateException("foobar"));
         assertThat(exception.status(), equalTo(RestStatus.INTERNAL_SERVER_ERROR));
+
+        exception = new ConcurrentSnapshotExecutionException("testRepo", "testSnap", "test");
+        assertSame(exception.status(), RestStatus.CONFLICT);
     }
 
     public void testGuessRootCause() {