diff --git a/packages/hydrooj/src/model/discussion.ts b/packages/hydrooj/src/model/discussion.ts
index 6ee3d34c..c0eba89a 100644
--- a/packages/hydrooj/src/model/discussion.ts
+++ b/packages/hydrooj/src/model/discussion.ts
@@ -288,7 +288,7 @@ export async function getVnode(domainId: string, type: number, id: string, uid?:
             tdoc.attend = tsdoc?.attend || tsdoc?.enroll;
         }
         return {
-            ...tdoc, type, id, hidden: false,
+            ...tdoc, type, id: _id, hidden: false,
         };
     }
     return {
diff --git a/packages/hydrooj/src/upgrade.ts b/packages/hydrooj/src/upgrade.ts
index bbcbcccb..1820ee9a 100644
--- a/packages/hydrooj/src/upgrade.ts
+++ b/packages/hydrooj/src/upgrade.ts
@@ -616,6 +616,20 @@ const scripts: UpgradeScript[] = [
         }
         return true;
     },
+    async function _84_85() {
+        return await iterateAllDomain(async ({ _id }) => {
+            const cursor = discussion.getMulti(_id, { parentType: document.TYPE_CONTEST });
+            for await (const ddoc of cursor) {
+                const parentId = new ObjectId(ddoc.parentId);
+                await discussion.edit(_id, ddoc.docId, { parentId });
+                try {
+                    await contest.get(_id, parentId);
+                } catch (e) {
+                    await discussion.del(_id, ddoc.docId);
+                }
+            }
+        });
+    },
 ];
 
 export default scripts;