We're investiging reports where some users are not able to login. They're getting an "Action not completed - an unknown error occurred" error.

Update: this problem only seems to be happening from certain countries. We noticed that Cloudflare, where we proxy the traffic through, is having problems with POST body payloads. That explains the problem. See: https://www.cloudflarestatus.com/incidents/652w59bvnbsj