diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 419f070ab71..780d22afbca 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -2327,12 +2327,29 @@ RestoreSlotFromDisk(const char *name)
 	 * NB: Changing the requirements here also requires adapting
 	 * CheckSlotRequirements() and CheckLogicalDecodingRequirements().
 	 */
-	if (cp.slotdata.database != InvalidOid && wal_level < WAL_LEVEL_LOGICAL)
-		ereport(FATAL,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("logical replication slot \"%s\" exists, but \"wal_level\" < \"logical\"",
-						NameStr(cp.slotdata.name)),
-				 errhint("Change \"wal_level\" to be \"logical\" or higher.")));
+	if (cp.slotdata.database != InvalidOid)
+	{
+		if (wal_level < WAL_LEVEL_LOGICAL)
+			ereport(FATAL,
+					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+					 errmsg("logical replication slot \"%s\" exists, but \"wal_level\" < \"logical\"",
+							NameStr(cp.slotdata.name)),
+					 errhint("Change \"wal_level\" to be \"logical\" or higher.")));
+
+		/*
+		 * In standby mode, the hot standby must be enabled. This check is
+		 * necessary to ensure logical slots are invalidated when they become
+		 * incompatible due to insufficient wal_level. Otherwise, if the
+		 * primary reduces wal_level < logical while hot standby is disabled,
+		 * logical slots would remain valid even after promotion.
+		 */
+		if (StandbyMode && !EnableHotStandby)
+			ereport(FATAL,
+					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+					 errmsg("logical replication slot \"%s\" exists on the standby, but \"hot_standby\" = \"off\"",
+							NameStr(cp.slotdata.name)),
+					 errhint("Change \"hot_standby\" to be \"on\".")));
+	}
 	else if (wal_level < WAL_LEVEL_REPLICA)
 		ereport(FATAL,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index 4628f9fb806..aeb79f51e71 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -345,6 +345,44 @@ $psql_subscriber{run} = IPC::Run::start(
 	\$psql_subscriber{subscriber_stderr},
 	IPC::Run::timeout($default_timeout));
 
+##################################################
+# Test that the standby requires hot_standby to be
+# enabled for pre-existing logical slots.
+##################################################
+
+# create the logical slots
+$node_standby->create_logical_slot_on_standby($node_primary, 'restart_test');
+$node_standby->stop;
+$node_standby->append_conf('postgresql.conf', qq[hot_standby = off]);
+
+# Use run_log instead of $node_standby->start because this test expects
+# that the server ends with an error during startup.
+run_log(
+	[
+		'pg_ctl',
+		'--pgdata' => $node_standby->data_dir,
+		'--log' => $node_standby->logfile,
+		'start',
+	]);
+
+# wait for postgres to terminate
+foreach my $i (0 .. 10 * $PostgreSQL::Test::Utils::timeout_default)
+{
+	last if !-f $node_standby->data_dir . '/postmaster.pid';
+	usleep(100_000);
+}
+
+# Confirm that the server startup fails with an expected error
+my $logfile = slurp_file($node_standby->logfile());
+ok( $logfile =~
+	  qr/FATAL: .* logical replication slot ".*" exists on the standby, but "hot_standby" = "off"/,
+	"the standby ends with an error during startup because hot_standby was disabled"
+);
+$node_standby->adjust_conf('postgresql.conf', 'hot_standby', 'on');
+$node_standby->start;
+$node_standby->safe_psql('postgres',
+	qq[SELECT pg_drop_replication_slot('restart_test')]);
+
 ##################################################
 # Test that logical decoding on the standby
 # behaves correctly.