Hello, I have the same issue since yesterday.
As far as I can tell, when SSH tunneling into the server running plex and accessing http://127.0.0.1:32400/web nothing was showing.
I followed first this: https://support.plex.tv/articles/204281528-why-am-i-locked-out-of-server-settings-and-how-do-i-get-in/ ( Remove Certain Entries > Linux ) and the server appeared again after restarting the process, however it cannot be claimed. When clicking on “Claim Server” the button spins for some time and comes back to the same state.
When accessing again the web UI through the tunnel, I see that trying to access this URL returns a 404 error:
(Some details removed for privacy).
Checking from a different computer, indeed if I curl this URL I get the same error code.
Is there an issue with the endpoint at https://plex.tv/api/claim?