Edit file on stopped container, that maybe fails to start - smile!

[Costas]

//src - https://stackoverflow.com/a/55593604/1320686

//copy the file outside container

docker container cp [container]:/etc/mysql/my.cnf container-my.cnf

//edit it and copy back:

docker container cp container-my.cnf [container]:/etc/mysql/my.cnf

you can use :

docker logs [container]

to see the exception.