Installer starts after upgrade to 6.5.4.1

I have upgraded from version 6.4.20.2 to 6.5.4.1. After that I wanted to log in as admin. Instead of the admin page, the Shopware installer started. What happened there? I do not want to do a reinstallation. I then ran the installer with a second new database. After that everything was ok again and the old database was active. But when I recreated the container, the installer was there again.