diff --git a/packages/backend/server/src/core/doc/adapters/userspace.ts b/packages/backend/server/src/core/doc/adapters/userspace.ts
index 14165ba5c9..b5fd9a2655 100644
--- a/packages/backend/server/src/core/doc/adapters/userspace.ts
+++ b/packages/backend/server/src/core/doc/adapters/userspace.ts
@@ -37,6 +37,10 @@ export class PgUserspaceDocStorageAdapter extends DocStorageAdapter {
     return false;
   }
 
+  override async rollbackDoc() {
+    return;
+  }
+
   override async getDoc(spaceId: string, docId: string) {
     return this.getDocSnapshot(spaceId, docId);
   }
@@ -137,10 +141,10 @@ export class PgUserspaceDocStorageAdapter extends DocStorageAdapter {
   protected async setDocSnapshot(snapshot: DocRecord) {
     // we always get lock before writing to user snapshot table,
     // so a simple upsert without testing on updatedAt is safe
-    await this.db.snapshot.upsert({
+    await this.db.userSnapshot.upsert({
       where: {
-        id_workspaceId: {
-          workspaceId: snapshot.spaceId,
+        userId_id: {
+          userId: snapshot.spaceId,
           id: snapshot.docId,
         },
       },
@@ -149,7 +153,7 @@ export class PgUserspaceDocStorageAdapter extends DocStorageAdapter {
         updatedAt: new Date(snapshot.timestamp),
       },
       create: {
-        workspaceId: snapshot.spaceId,
+        userId: snapshot.spaceId,
         id: snapshot.docId,
         blob: Buffer.from(snapshot.bin),
         createdAt: new Date(snapshot.timestamp),
diff --git a/packages/backend/server/src/core/sync/gateway.ts b/packages/backend/server/src/core/sync/gateway.ts
index 9f22099449..b026c430ef 100644
--- a/packages/backend/server/src/core/sync/gateway.ts
+++ b/packages/backend/server/src/core/sync/gateway.ts
@@ -11,6 +11,7 @@ import { Socket } from 'socket.io';
 import { diffUpdate, encodeStateVectorFromUpdate } from 'yjs';
 
 import {
+  AlreadyInSpace,
   CallTimer,
   Config,
   DocNotFound,
@@ -579,8 +580,7 @@ abstract class SyncSocketAdapter {
 
   assertNotIn(spaceId: string, roomType: RoomType = 'sync') {
     if (this.client.rooms.has(this.room(spaceId, roomType))) {
-      // TODO(@forehalo): use new AlreadyInSpace({ spaceId }) instead
-      throw new NotInSpace({ spaceId });
+      throw new AlreadyInSpace({ spaceId });
     }
   }
 
@@ -621,11 +621,6 @@ class WorkspaceSyncAdapter extends SyncSocketAdapter {
     super(SpaceType.Workspace, client, storage);
   }
 
-  // backward compatibility
-  override room(spaceId: string, roomType: RoomType = 'sync') {
-    return Room(spaceId, roomType);
-  }
-
   override push(spaceId: string, docId: string, updates: Buffer[]) {
     const id = new DocID(docId, spaceId);
     return super.push(spaceId, id.guid, updates);