diff --git a/changelog.d/342.bugfix b/changelog.d/342.bugfix
new file mode 100644
index 00000000..d7284471
--- /dev/null
+++ b/changelog.d/342.bugfix
@@ -0,0 +1 @@
+Leave the new room on room upgrade if the upgrade was not successful.
\ No newline at end of file
diff --git a/src/components/room-upgrade-handler.ts b/src/components/room-upgrade-handler.ts
index 7f62ca71..104f5830 100644
--- a/src/components/room-upgrade-handler.ts
+++ b/src/components/room-upgrade-handler.ts
@@ -150,6 +150,7 @@ export class RoomUpgradeHandler {
             log.error(
     `Room doesn't have a matching predecessor (expected: ${oldRoomId}, got: ${predecessor.room_id}), not bridging.`
             );
+            await intent.leave(newRoomId);
             return false;
         }
         const asBot = this.bridge.getBot();
@@ -157,6 +158,7 @@ export class RoomUpgradeHandler {
             const success = await this.migrateStoreEntries(oldRoomId, newRoomId);
             if (!success) {
                 log.error("Failed to migrate room entries. Not continuing with migration.");
+                await intent.leave(newRoomId);
                 return false;
             }
         }