Error 500 when creating a milestone
Summary
When I try to create a milestone, I get a 500 error. It's an imported repository from github and two milestones imported from it.
Steps to reproduce
No particular step, with or without description, dates, or only with a title, I always get a 500 error.
Example Project
https://gitlab.com/DMaugmentedTeam/DMA
What is the current bug behavior?
500 error instead of milestone creation
What is the expected correct behavior?
A newly created milestone
Output of checks
This bug happens on GitLab.com