By using the (incrementel) backup function which Server4You provides. In addition I have some scripts running to backup some important stuff on a daily basis. With this I was able to bring the server back to the state before the plesk upgrade. For now, the Plesk updates are disabled until the...
I have the same issue using a vserver from Server4You. Meanwhile I recovered the state before upgrading Plesk to 18.0.40 until the fixed version is available.