Restore Admin Passwort

After restarting the MC docker instance on the server I was unable to log in with the user I used to log in to the system all the time. I am sure that the user and password are correct. What could be the reason? How can I recover the password?

You may try to run docker-compose down and docker-compose up -d. I just experienced the same after I restarted the nginx container… After doing so I can use the username and password to login again.