SOLVED: Playback Error. Playback failed due to a fatal player error.

[TheDreadPirate]

How are you starting Jellyfin? Are you running the docker command directly or using docker compose?

Also, looking at the tutorial and the output from docker inspect, you are not putting your permanent Jellyfin data in a private location. It is in /var/lib/docker/volumes. Which is technically fine, but not ideal.

The log confirms that it is A) looking in the right place for ffmpeg and B) failing to find it for some reason.

Try doing this.

1) Stop the jellyfin container.
2) Run this command. "sudo docker system prune -a". This will delete the temporary file system the container created (will not delete permanent data).
3) Start the jellyfin container. The previous command will force docker to pull down the jellyfin image again and recreate the virtual file system. Including, hopefully, jellyfin-ffmpeg within that virtual file system.