Gitlab Pages: Bad Content-Type Return for 404 Pages

Summary

Gitlab Pages: Bad Content-Type Return for 404 Pages

Steps to reproduce

visit: http://sss.gitlab.io (any link that doesn't exists)

Expected behavior

It should return a 404 HTML page, not a Text Html Code

Relevant logs and/or screenshots

Output of checks

Results of GitLab Application Check

Results of GitLab Environment Info

Possible fixes

Miss the Content-Type Head, maybe nginx proxy configurion, maybe the backend code