My server is running Ubuntu 20, text-only. It is regularly maintained with all the latest updates and is due for a release upgrade which I hesitate to perform because of an insidious shutdown every Sunday at 12 midnight.
It began when one of the attached disks broke down but the shutdown persisted when the disk was replaced. The disk was a peripheral one for data, not system files.
The folder at /run/systemd/shutdown is empty. I've also examined various log files but nothing jumps out.
I have no atd scheduled commands.
I have a number of cron commands but none to sun on Sunday midnight.
Suggestions please?