Got exactly the same issue. Spend some time to investigate, but found the exact reason of the issue.
Sometimes, for whatever reason, it is possible that incorrect session data may appear in /usr/share/hassio/ingress.json. As far as I understand, session data is being stored in this file.
ingress.py doesn’t validate data from this json file, and passes timestamp to utility function, where bad timestamp causes error.
Solution is to remove all or most sessions from /usr/share/hassio/ingress.json file.
I’m going to propose fix, validating sessions data in ingress.py to avoid future issues with this.