diff --git a/src/common/backend/utils/misc/guc.cpp b/src/common/backend/utils/misc/guc.cpp
index 7c94eb760..8f74e6231 100644
--- a/src/common/backend/utils/misc/guc.cpp
+++ b/src/common/backend/utils/misc/guc.cpp
@@ -4921,7 +4921,7 @@ static void InitConfigureNamesInt()
                 gettext_noop("Sets the maximum number of simultaneously running WAL sender processes."),
                 NULL},
             &g_instance.attr.attr_storage.max_wal_senders,
-            4,
+            16,
             0,
             MAX_BACKENDS,
             NULL,
@@ -8093,7 +8093,7 @@ static void InitConfigureNamesString()
                  NULL,
                  GUC_LIST_INPUT},
                 &u_sess->attr.attr_storage.SyncRepStandbyNames,
-                "",
+                "*",
                 check_synchronous_standby_names,
                 assign_synchronous_standby_names,
                 NULL},
diff --git a/src/test/ha/testcase/multi_standby_single/params.sh b/src/test/ha/testcase/multi_standby_single/params.sh
index 07807a71e..8c12d93cc 100644
--- a/src/test/ha/testcase/multi_standby_single/params.sh
+++ b/src/test/ha/testcase/multi_standby_single/params.sh
@@ -56,6 +56,14 @@ function test_1()
   gs_guc set -Z datanode -D $primary_data_dir -c "synchronous_standby_names = 'jane'"
   start_cluster
   check_asynchronous_commit "datanode1" 4
+  
+  echo "test synchronous_standby_names = ''"
+  kill_cluster
+  gs_guc set -Z datanode -D $primary_data_dir -c "synchronous_commit = on"
+  gs_guc set -Z datanode -D $primary_data_dir -c "synchronous_standby_names = ''"
+  gs_guc set -Z datanode -D $primary_data_dir -c "most_available_sync = on"
+  start_cluster
+  check_asynchronous_commit "datanode1" 4
 }
 
 function tear_down() {