@huber70
A good BBQ takes time to heat up and to eat. Especially if accompanied with a good glas of whatever you like.
1) Retry
docker stop photoprism_mariadb_1
docker rm photoprism_mariadb_1
docker ps [should be empty, if not docker rm -f photoprism_mariadb_1 , then check again]
3) Remove any directory named
storage in /home/pi so that all databases with possibly wrong info are removed.
4) I hope we now are back to an empty canvas.
5) then try again......
6) if it does not work try my slightly alternative setup without mariadb, but yours is better.