diff --git a/src/protocol/pool_proto_modules.c b/src/protocol/pool_proto_modules.c
index 11befe979..e030e7b6d 100644
--- a/src/protocol/pool_proto_modules.c
+++ b/src/protocol/pool_proto_modules.c
@@ -222,20 +222,39 @@ SimpleQuery(POOL_CONNECTION *frontend,
 	strlcpy(query_string_buffer, contents, sizeof(query_string_buffer));
 
 	/*
-	 * Check if extended query protocol message ended.  If not, reject the
-	 * query and raise an error to terminate the session to avoid hanging up.
-	 * However if we are processing a reset query (frontend == NULL), we skip
-	 * the check as we don't want to raise a error.
+	 * Check if extended query protocol message ended.  If not, process any
+	 * pending response from backend using ProcessBackendResponse().  However
+	 * if we are processing a reset query (frontend == NULL), we skip the
+	 * check as we don't need to care about any pending response from backend.
 	 */
 	if (SL_MODE)
 	{
+		int	state;
+		short	num_fields;
+
 		if (frontend != NULL &&
 			(pool_is_doing_extended_query_message() ||
-			 pool_pending_message_head_message()))
-
-			ereport(FATAL,
+			 pool_pending_message_exists()))
+		{
+			ereport(DEBUG1,
 					(errmsg("simple query \"%s\" arrived before ending an extended query message",
 							query_string_buffer)));
+
+			/* if pending message exists, process it */
+			while (pool_pending_message_exists())
+			{
+				/*
+				 * read_kind_from_backend requires that query is inprogress
+				 * and doing extended query state because it needs to refer to
+				 * proper query context in session context.
+				 */
+				pool_set_query_in_progress();
+				pool_set_doing_extended_query_message();
+				/* process pending responses from backend */
+				ProcessBackendResponse(frontend, backend, &state, &num_fields);
+			}
+		}
+		pool_unset_doing_extended_query_message();
 	}
 
 	/* show ps status */
@@ -3080,6 +3099,12 @@ ProcessFrontendResponse(POOL_CONNECTION *frontend,
 	return status;
 }
 
+/*
+ * Read one backend response and process it.
+ *
+ * state: used for processing reset query
+ * num_fields: used in V2 protocol
+ */
 POOL_STATUS
 ProcessBackendResponse(POOL_CONNECTION *frontend,
 					   POOL_CONNECTION_POOL *backend,