Jellyfin not restarting after update of Docker Engine container on Asustor NAS

[Lynd148]

Thank you very much for your prompt response. It would seem that my problem is local to my system. I will shut down Jellyfin before doing any future updates and will do a backup of Docker/Jellyfin before updating as you suggest.
Regarding second part of my question can you point me to any reliable info about exactly what needs to be deleted if for any reason one needs to do a new 'vanilla' installation of Jellyfin?