Can't connect to local MySQL server through socket

My nextcloudpi docker container did not work properly from this morning on. I removed the container and started a new one, but still have these errors.

docker run -d -p 4443:4443 -v ncdata:/data -v /media/simon/:/extHDD/ --name nextcloudpi --network nextcloudpi ownyourbits/nextcloudpi

2022-11-23T10:13:15.828835255Z Making /usr/local/bin persistent ...
2022-11-23T10:13:16.266561453Z Making /etc/apache2/sites-available persistent ...
2022-11-23T10:13:16.269576147Z mv: failed to access '/data/etc/apache2/sites-available': Too many levels of symbolic links
2022-11-23T10:13:16.630811208Z Starting Redis
2022-11-23T10:13:16.697825463Z Starting Cron
2022-11-23T10:13:16.704162037Z Starting Postfix
2022-11-23T10:13:17.320080375Z ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/run/mysqld/mysqld.sock' (2)
2022-11-23T10:13:17.490998177Z Init done

Do I have to delete nc data first?

 docker volume inspect ncdata
        "CreatedAt": "2022-11-23T11:13:15+01:00",
        "Driver": "local",
        "Labels": null,
        "Mountpoint": "/var/lib/docker/volumes/ncdata/_data",
        "Name": "ncdata",
        "Options": null,
        "Scope": "local"

I do not know why, but my whole server seemed to have stopped this morning. So maybe the database is corrupt since then.