500 Error When Creating Merge Requests

We are using GitLab for our project here: cip-project / cip-kernel / cip-kernel-sec · GitLab
When we create a merge request for this project, Gitlab returns a 500 error.
One example is create a merge request to merge ebardie/import_from_debian_stable_branches into master.
After the standard New Merge Request page, with or without entering additional information,
clicking on the Submit merge request button results in a 500 error.

Any assistance on the issue would be highly appreciated.