diff --git a/proxy_components/mock-engine-store/src/mock_store/mock_fast_add_peer_impls.rs b/proxy_components/mock-engine-store/src/mock_store/mock_fast_add_peer_impls.rs
index 9a30480fc98..a1bccd51b89 100644
--- a/proxy_components/mock-engine-store/src/mock_store/mock_fast_add_peer_impls.rs
+++ b/proxy_components/mock-engine-store/src/mock_store/mock_fast_add_peer_impls.rs
@@ -41,6 +41,9 @@ pub(crate) unsafe extern "C" fn ffi_apply_fap_snapshot(
                 "region_id" => region_id,
                 "peer_id" => peer_id,
             );
+            if assert_exist {
+                panic!("should exist region_id={} peed_id={}", region_id, peer_id);
+            }
             return 0;
         }
     };