One fix from Alex is to reboot your computer to resolve this issue.

If the issue persists, or returns, another fix I have is from Ticket 1023528

From IAMO:

"If the problem is only chrome, the error we've seen in the past is that his requests exceeded the header size limit.

If the user only sees this problem in Chrome, it's a known problem with the browser outlined here - https://productforums.google.com/forum/#!topic/chrome/G82JDzzoRio.

That URL also has suggested steps to fix the problem.
If the user still sees the error - please provide the user's IP address and exact steps taken to authenticate."

Browser not supported