diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index fabba3bacd..519673a2e3 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -2729,6 +2729,12 @@ ReindexRelationConcurrently(Oid relationOid, int options)
 				/* Open relation to get its indexes */
 				heapRelation = table_open(relationOid, ShareUpdateExclusiveLock);
 
+				/* A system catalog cannot be reindexed concurrently */
+				if (IsSystemRelation(heapRelation))
+					ereport(ERROR,
+							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+							 errmsg("cannot reindex a system catalog concurrently")));
+
 				/* Add all the valid indexes of relation to list */
 				foreach(lc, RelationGetIndexList(heapRelation))
 				{
@@ -2814,17 +2820,11 @@ ReindexRelationConcurrently(Oid relationOid, int options)
 			{
 				Oid			heapId = IndexGetRelation(relationOid, false);
 
-				/* A shared relation cannot be reindexed concurrently */
-				if (IsSharedRelation(heapId))
-					ereport(ERROR,
-							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-							 errmsg("concurrent reindex is not supported for shared relations")));
-
 				/* A system catalog cannot be reindexed concurrently */
 				if (IsSystemNamespace(get_rel_namespace(heapId)))
 					ereport(ERROR,
 							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-							 errmsg("concurrent reindex is not supported for catalog relations")));
+							 errmsg("cannot reindex a system catalog concurrently")));
 
 				/* Save the list of relation OIDs in private context */
 				oldcontext = MemoryContextSwitchTo(private_context);
diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out
index 326dc44177..ab8b1eb3fe 100644
--- a/src/test/regress/expected/create_index.out
+++ b/src/test/regress/expected/create_index.out
@@ -2092,10 +2092,6 @@ BEGIN;
 REINDEX TABLE CONCURRENTLY concur_reindex_tab;
 ERROR:  REINDEX CONCURRENTLY cannot run inside a transaction block
 COMMIT;
-REINDEX TABLE CONCURRENTLY pg_database; -- no shared relation
-ERROR:  concurrent index creation on system catalog tables is not supported
-REINDEX TABLE CONCURRENTLY pg_class; -- no catalog relations
-ERROR:  concurrent index creation on system catalog tables is not supported
 REINDEX SYSTEM CONCURRENTLY postgres; -- not allowed for SYSTEM
 ERROR:  concurrent reindex of system catalogs is not supported
 -- Warns about catalog relations
diff --git a/src/test/regress/expected/reindex_catalog.out b/src/test/regress/expected/reindex_catalog.out
index 142616fccb..70a3f906da 100644
--- a/src/test/regress/expected/reindex_catalog.out
+++ b/src/test/regress/expected/reindex_catalog.out
@@ -31,3 +31,28 @@ REINDEX INDEX pg_index_indexrelid_index; -- non-mapped, non-shared, critical
 REINDEX INDEX pg_index_indrelid_index; -- non-mapped, non-shared, non-critical
 REINDEX INDEX pg_database_oid_index; -- mapped, shared, critical
 REINDEX INDEX pg_shdescription_o_c_index; -- mapped, shared, non-critical
+-- Check that REINDEX CONCURRENTLY is forbidden with system catalogs.
+-- For whole tables.
+REINDEX TABLE CONCURRENTLY pg_class; -- mapped, non-shared, critical
+ERROR:  cannot reindex a system catalog concurrently
+REINDEX TABLE CONCURRENTLY pg_index; -- non-mapped, non-shared, critical
+ERROR:  cannot reindex a system catalog concurrently
+REINDEX TABLE CONCURRENTLY pg_operator; -- non-mapped, non-shared, critical
+ERROR:  cannot reindex a system catalog concurrently
+REINDEX TABLE CONCURRENTLY pg_database; -- mapped, shared, critical
+ERROR:  cannot reindex a system catalog concurrently
+REINDEX TABLE CONCURRENTLY pg_shdescription; -- mapped, shared non-critical
+ERROR:  cannot reindex a system catalog concurrently
+-- For system indexes
+REINDEX INDEX CONCURRENTLY pg_class_oid_index; -- mapped, non-shared, critical
+ERROR:  cannot reindex a system catalog concurrently
+REINDEX INDEX CONCURRENTLY pg_class_relname_nsp_index; -- mapped, non-shared, non-critical
+ERROR:  cannot reindex a system catalog concurrently
+REINDEX INDEX CONCURRENTLY pg_index_indexrelid_index; -- non-mapped, non-shared, critical
+ERROR:  cannot reindex a system catalog concurrently
+REINDEX INDEX CONCURRENTLY pg_index_indrelid_index; -- non-mapped, non-shared, non-critical
+ERROR:  cannot reindex a system catalog concurrently
+REINDEX INDEX CONCURRENTLY pg_database_oid_index; -- mapped, shared, critical
+ERROR:  cannot reindex a system catalog concurrently
+REINDEX INDEX CONCURRENTLY pg_shdescription_o_c_index; -- mapped, shared, non-critical
+ERROR:  cannot reindex a system catalog concurrently
diff --git a/src/test/regress/sql/create_index.sql b/src/test/regress/sql/create_index.sql
index f29b8ca826..7bcc79b458 100644
--- a/src/test/regress/sql/create_index.sql
+++ b/src/test/regress/sql/create_index.sql
@@ -838,8 +838,6 @@ DROP TABLE concur_reindex_part;
 BEGIN;
 REINDEX TABLE CONCURRENTLY concur_reindex_tab;
 COMMIT;
-REINDEX TABLE CONCURRENTLY pg_database; -- no shared relation
-REINDEX TABLE CONCURRENTLY pg_class; -- no catalog relations
 REINDEX SYSTEM CONCURRENTLY postgres; -- not allowed for SYSTEM
 -- Warns about catalog relations
 REINDEX SCHEMA CONCURRENTLY pg_catalog;
diff --git a/src/test/regress/sql/reindex_catalog.sql b/src/test/regress/sql/reindex_catalog.sql
index 2180ee5791..72d2996132 100644
--- a/src/test/regress/sql/reindex_catalog.sql
+++ b/src/test/regress/sql/reindex_catalog.sql
@@ -34,3 +34,18 @@ REINDEX INDEX pg_index_indexrelid_index; -- non-mapped, non-shared, critical
 REINDEX INDEX pg_index_indrelid_index; -- non-mapped, non-shared, non-critical
 REINDEX INDEX pg_database_oid_index; -- mapped, shared, critical
 REINDEX INDEX pg_shdescription_o_c_index; -- mapped, shared, non-critical
+
+-- Check that REINDEX CONCURRENTLY is forbidden with system catalogs.
+-- For whole tables.
+REINDEX TABLE CONCURRENTLY pg_class; -- mapped, non-shared, critical
+REINDEX TABLE CONCURRENTLY pg_index; -- non-mapped, non-shared, critical
+REINDEX TABLE CONCURRENTLY pg_operator; -- non-mapped, non-shared, critical
+REINDEX TABLE CONCURRENTLY pg_database; -- mapped, shared, critical
+REINDEX TABLE CONCURRENTLY pg_shdescription; -- mapped, shared non-critical
+-- For system indexes
+REINDEX INDEX CONCURRENTLY pg_class_oid_index; -- mapped, non-shared, critical
+REINDEX INDEX CONCURRENTLY pg_class_relname_nsp_index; -- mapped, non-shared, non-critical
+REINDEX INDEX CONCURRENTLY pg_index_indexrelid_index; -- non-mapped, non-shared, critical
+REINDEX INDEX CONCURRENTLY pg_index_indrelid_index; -- non-mapped, non-shared, non-critical
+REINDEX INDEX CONCURRENTLY pg_database_oid_index; -- mapped, shared, critical
+REINDEX INDEX CONCURRENTLY pg_shdescription_o_c_index; -- mapped, shared, non-critical