Mattermost on gitlab has Error Uable to Save the token at login

I have a Mattermost instance running on a gitlab server. I’m using the gitlab server for SSO. Both Gitlab and Mattermost are using HTTPS, with an SSL cert for an authority. The system worked fine until the last Gitlab update. Now Mattermost works for a few min after booting the system, then fails with “Error Unable to save the token.” In the logs it appears Mattermost can no longer contact the Gitlab server. They are running on the same machine. I turned off the IDS, IPS, and UFW to try to troubleshoot this. But it still seems to fail. Anybody have any idea of what I could take a look at next?