500 error when creating and deleting merge requests

Summary

I'm getting 500 errors when I push to a branch that's on a merge request. Also getting 500 error when creating new merge requests and when deleting new merge requests. New merge requests show as having 0 changes.

Steps to reproduce

Create a new merge request

Relevant logs and/or screenshots

git says:

Total 0 (delta 0), reused 0 (delta 0), pack-reused 0
remote: GitLab: http post to gitlab api /post_receive endpoint: 500 Internal Server Error

Output of checks

This bug happens on GitLab.com