Browsing the app fine today and now I'm repeatedly getting "400 Bad Request: Request Header Or Cookie Too Large" on every page. Clearing the cache in app is not doing anything. Can browse fine in Chrome.
Alright, I'll double-check that clearing cookies actually clears cookies.
As for the underlying issue, what would help if for you to give us the contents of your cookie (privately, to firstname.lastname@example.org ) if it happens again. I would've asked you to do it for this time but it was already too late :)