500 error SSO continuation

Continuing the discussion from Reports of user logged out twice today - related to recent auth tokens changes?:

For what it’s worth, I just had this error myself with beta 8 release (which was after your most recent fix here). I’m upgrading to beta 9 that was just posted in hopes something there has fixed it further.

What device is this on?

Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/602.4.8 (KHTML, like Gecko) Version/10.0.3 Safari/602.4.8

Is this reproducible? Did you randomly get logged out? Are you able to log back in?

I logged in as a new login in Chrome, and when I did that — it fixed this problem back in Safari.

This does not make sense, I think a rate limiter simply timed out.

What does that mean?

There is a rate limiter that could cause an error in previous builds. Once it expires (after a minute) the error should vanish.