You've gone offline. Attempting to reconnect

I get this error constantly now, after my 10.2 upgrade, often in the middle of doing work on the site or simply browsing.

ETA: My console is laden w/ "Failed to load resource: the server responded with a status of 403 (Forbidden)" and "socket.ashx/negotiate?(full URL elided)". I have 2 web servers. 

This, along with your other thread do make we wonder if some broader issue may be at work here. I'd still recommend opening a support ticket to help more deeply analyze the upgrade and potentially review an HTTP trace. My apologies if you've already taken these steps.