diff --git a/lib/platform/gitlab/index.ts b/lib/platform/gitlab/index.ts
index 2aebab7e83403cf6c3447cf7963e84133ce18b3a..5969858561453d66b56c9b92339dc88202807b5e 100644
--- a/lib/platform/gitlab/index.ts
+++ b/lib/platform/gitlab/index.ts
@@ -505,7 +505,7 @@ export async function mergePr(iid: number): Promise<boolean> {
       return false;
     }
     if (err.statusCode === 406) {
-      logger.debug('PR not acceptable for merging');
+      logger.debug({ err }, 'PR not acceptable for merging');
       return false;
     }
     logger.debug({ err }, 'merge PR error');