If you see that on a docker ps, showing a container with a status “Exited (255)“, that means its main entrpypoint/command process stopped with that status.
And 255 simply means “there was an error”, but does not tell you much beside that.
Hence the article “5 ways to debug an exploding Docker container” from Tim Perry, to investigate further:
docker logs <container_id>
docker stats <container_id>
docker cp <container_id>:/path/to/useful/file /local-path
docker exec -it <container_id> /bin/bash
docker commit <container_id> my-broken-container && \
docker run -it my-broken-container /bin/bash