Thank you for sharing these logs. I understand that the issue may no longer be relevant, but I found your question quite interesting and took the opportunity to review it to better understand what might have caused the login problem after the update.

From what I can see in the logs, there doesn't appear to be anything suspicious - everything seems to be functioning as expected to me. After updating to a new version, GitLab prompts for reauthentication. If the login form fields were not displaying, it could be related to a front-end issue. Have you tried recompiling your assets? The official GitLab documentation might be helpful in this case. Additionally, clearing your browser cache could also resolve such display issues.

However if the problem was still reproducible on a clean install with your data, that might indicate an issue with the data itself or the configuration settings, rather than with the GitLab system environment. Possible causes could include corrupted or incomplete database entries, misconfigurations, or even something customization related. For example, I noticed in the logs that a custom header logo is being used:

"/uploads/-/system/appearance/header_logo/1/ytlc.png"

Since this post is 6 years old, I am curious were you eventually able to fix the issue? If so, what was the fix?