Cannot SignIn anymore via WebUI after configuration changes

We are about to start using a self hosted GitLab-EE and were doing some “last” configuration changes as an Admin via the WebUI, mainly about whitelisting domains, blocking people from SigningUp, Enforcing 2FA.

After logout the WebUI is showing the attached reduced page and we are not able to do anything regarding SignIn anymore. Exploring is still possible though.

My question is how can we revert some of the last config changes in order to SignIn again?

Is there any other API except WebUI available I can change the configuration with? Or somehow change the config via editing config files etc?

from nginx access.log:
“GET /users/sign_in HTTP/2.0” 200 3234 “” “Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:75.0) Gecko/20100101 Firefox/75.0”
followed by a couple of assets.

No entries from nginx error.log.

I wasn’t able to find any help for the related issue anywhere.

To me it doesn’t make any sense to be able to configure the System via WebUI so it isn’t anymore usable via WebUI (no Login field available anymore). Seems like a bug to me.

Thanks a lot,