This one has been hounding me in Firefox for a while, not had a chance to repro in any other browsers yet. Finally found the cause. Repro steps: Login to Spectrum on Firefox Load My Hangar section of RSI site Click "Ship Upgrades" Reload Spectrum At this point, you should be greeted by a never ending Spectrum Loading screen. Debug tools will show you that the websocket connection is failing with a 413 error from cloudfront. The cause has been discovered to be the "rsi-account-auth" token that is generated when loading the new upgrades screen. Workaround: Delete the "rsi-account-auth" cookie via Developer Tools. Spectrum will immediately load.