Room Not Creating Database In UI-Tests

I am using a Room database inside my project and it works in production including the UI-Tests (with Espresso) until Android 8. On Android 9 currently my UI-Tests fail because the

Solution 1:

It turned out that a close() was missing for the database after the Migration. In the production App everything was fine but inside the Tests + on Emulator the described error came up. Maybe its helpful for someone else!