Unable to login after VM restart

I have Home Assistant OS 5.13, homeassistat 2021.5.5 running as a VM on Synology DSM. I had to restart the VM with HA, after that I was unable to login via web UI or app as the existing credentials returned “Invalid username or password”.
Following guide I'm Locked Out! - Home Assistant I attempted to reset the password via the CLI via the host terminal: no success as auth reset --username "name" --password "pass" gives “Error: Unkown error, see supervisor”.
From the CLI with supervisor logs I see at the end (how to page?) the warning [supervisor.auth] The user 'name' is not registered.
Via the CLI I see few errors, unfortunately I do not know how to copy text from the Synology web console – a screenshot

FWIW the HA observer at :4357 shows Supervisor: Connected.

I have a recent HA snapshot and I could destroy the VM and restart from scratch: I would like to find out if and how I can recover HA from a simple VM restart first.
What can I check and do next?