diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index 21ef15f..95c34fe 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -291,6 +291,11 @@ CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
 	bool		create_slot;
 	List	   *publications;
 
+	if (!IsUnderPostmaster)
+		ereport(FATAL,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+			errmsg("subscription commands are not supported by single-user servers")));
+
 	/*
 	 * Parse and check options.
 	 * Connection and publication should not be specified here.
@@ -583,6 +588,12 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
 	bool		update_tuple = false;
 	Subscription   *sub;
 
+	if (!IsUnderPostmaster)
+		ereport(FATAL,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+			errmsg("subscription commands are not supported by single-user servers")));
+
+
 	rel = heap_open(SubscriptionRelationId, RowExclusiveLock);
 
 	/* Fetch the existing tuple. */
@@ -780,6 +791,11 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	WalReceiverConn	   *wrconn = NULL;
 	StringInfoData		cmd;
 
+	if (!IsUnderPostmaster)
+		ereport(FATAL,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+			errmsg("subscription commands are not supported by single-user servers")));
+
 	/*
 	 * Lock pg_subscription with AccessExclusiveLock to ensure
 	 * that the launcher doesn't restart new worker during dropping