Ever since I upgraded to the latest Plex server software, Plex has been telling me there's an unclaimed server. However, trying to claim that server always fails and I am asked to sign in first (even though I was already signed in) and that always fails.
I'm using an Ubuntu Desktop 14.04LTS installation with a projector, on a home wired network with Internet access. I've manually signed out of my server, manually signed out of the plex.tv website, disabled my adblocker (Adblock Plus on Chrome) restarted the computer, and tried again -- same error.
I also noticed that my server says there's an upgrade available even though that's the exact version I am already running (plexmediaserver_1.1.3.2700-6f64a8d_amd64.deb). I have re-downloaded and installed it on top of my existing software, but the situation remains.
I dug out an older version (plexmediaserver_1.0.0.2261-a17e99e_amd64.deb) and installed that on top of my existing software -- and both problems went away! The dashboard no longer reports an unclaimed server, and I have no log-in errors.
I notice many similar problem reports, but none mention downgrading as a successful "solution", but at least for me it solves the problem. This tells me it's not a firewall issue or otherwise related to the network; it seems directly linked to the version of the Plex server software. Could there be a bug in the plexmediaserver_1.1.3.2700 version that is causing this?