Thanks for the detailed repro steps, @fab2! Since recent Mattermost images were slimmed down (hence the size drop) they no longer include bash, so can you try using a POSIX shell instead (e.g., docker exec -it <container> sh or docker run --rm -it --entrypoint sh mattermost/mattermost-team-edition:10.11.1)? Or extend the image to add bash if you need it.