An error occurred while merging. Try again.

This started happening out of the blue after some of the recent upgrades.

A developer creates a merge request, I approve merge request, merge request is simple without any reason to fail, I click on “MERGE” button and I get

I check the master and all the changes are merged to master ?!?!? I can’t find “what failed”

I have no idea why merges are failing nor now to get actual log data on what is failing. anyone can help?