On June 9th at 11:57UTC our support staff noticed an issue with logging in to the Knowledge Base. The issue was resolved by 13:43 UTC.
Hotjar's Knowledge Base uses Single Sign-On to log users into the Knowledge Base. Due to an internal update, the Single Sign-On stopped working.
The upgrade was to a newer version of the underlying software Hotjar uses. This caused an incompatibility to how we handled the tokens generated and prevented users from logging in.
We will hold an internal postmortem and update this report later.