Seafile Community Edition 12.0 Available for Testing! New Navigation and Viewing Experience, Enhanced SeaDoc Functions, New Knowledge Base and More

I’m currently in the middle of upgrading my (outdated) seafile 11 and obviously doing step upgrade (11->12) and after startup I’m getting same error:

seafile        | 2026-01-07T12:49:00.190754219Z -----------------------------------------------------------------
seafile        | 2026-01-07T12:49:00.190782163Z Upgraded your seafile server successfully.
seafile        | 2026-01-07T12:49:00.190812626Z -----------------------------------------------------------------
seafile        | 2026-01-07T12:49:00.190836089Z
seafile        | 2026-01-07T12:49:00.210807146Z
seafile        | 2026-01-07T12:49:00.252350957Z Cannot find JWT_PRIVATE_KEY value from environment, try to read .env file.
seafile        | 2026-01-07T12:49:00.252454550Z Error: .env file not found.
seafile        | 2026-01-07T12:49:00.252480864Z Please follow the upgrade manual to set the .env file.
seafile        | 2026-01-07T12:49:00.252502531Z
seafile        | 2026-01-07T12:49:00.255908407Z Traceback (most recent call last):
seafile        | 2026-01-07T12:49:00.256010537Z   File "/scripts/start.py", line 94, in <module>
seafile        | 2026-01-07T12:49:00.256394480Z     main()
seafile        | 2026-01-07T12:49:00.258038844Z   File "/scripts/start.py", line 79, in main
seafile        | 2026-01-07T12:49:00.258133418Z     call('{} start'.format(get_script('seafile.sh')))
seafile        | 2026-01-07T12:49:00.258161510Z   File "/scripts/utils.py", line 70, in call
seafile        | 2026-01-07T12:49:00.258183288Z     return subprocess.check_call(*a, **kw)
seafile        | 2026-01-07T12:49:00.258472565Z            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
seafile        | 2026-01-07T12:49:00.258530972Z   File "/usr/lib/python3.12/subprocess.py", line 413, in check_call
seafile        | 2026-01-07T12:49:00.259045044Z     raise CalledProcessError(retcode, cmd)
seafile        | 2026-01-07T12:49:00.260495057Z subprocess.CalledProcessError: Command '/opt/seafile/seafile-server-12.0.14/seafile.sh start' returned non-zero exit status 255.

Any idea? This thread: Error setting up docker install seems to suggest rights/permissions issues but it was working fine before…

I tried running as non-root (vide Run Seafile as non root user inside docker - Seafile Admin Manual) but no luck.

Any idea?