Unable to log in after restoring from backup. Existing logged-in devices work without issues.

[csolisr]

Describe the bug

After restoring from a backup, it's no longer possible to log in using the standard CAS login flow. Existing accounts with a valid login are still able to use the platform unimpeded, but new devices are unable to log in.

Context

• Hardware: Dedicated x86 computer
• YunoHost version: 12.0.6
• I have access to my server: Through SSH, webadmin, direct access
• Are you in a special context or did you perform some particular tweaking on your YunoHost instance?: yes
  • If yes, please explain: Recently reinstalled from a backup; using an external VPS to bypass NAT restrictions
• Using, or trying to install package version/branch: 1.117.0~ynh1

Steps to reproduce

• Restore Synapse and Element from an existing backup.
• Open a web browser to your Element installation, e.g. https://chat.example.net .
• Click on "Log in", ensure your base server is correct, then click on "Continue with CAS".

Expected behavior

The standard login workflow should commence, using CAS to validate the user's credentials and then returning to Element's dashboard.

Logs

The site redirects in my case to https://azkware.net/_matrix/cas_server.php/login?service=https%3A%2F%2Fazkware.net%2F_matrix%2Fclient%2Fr0%2Flogin%2Fcas%2Fticket%3FredirectUrl%3Dhttps%253A%252F%252Fchat.azkware.net%252F with an error 404 and the message "File not found."

[csolisr]

Just found the error, for some reason the owner for /var/www/synapse were set to be element, not synapse. A quick chown solved the issue for me.