Can't login into my Gitlab account via Firefox (error 422)

It is amazing how many posts have gitlab forums about this issue and most of them are not solved.
It seems like in my case this only happens on Firefox.
I tried to login via username, email, OAuth, nothing works on Firefox.

Thanks in advance.

Does it work on other browsers? Do you have any extension installed?

What version of Firefox? What OS are you using?
Have you tried going to directly instead of the “go back” link in the screenshot? (you might already be logged into an account via one method and you’re trying to log in with a different account)

I have exactly the same problem form many months for personal Gitlab AND

OS: Arch
Browsers: Firefox for Arch and Firefox developer edition (with any extensions)

From what I could see during the login process a strange cookie is returned by the server:

date:    Thu, 24 Sep 2020 09:50:46 GMT
expires:    Fri, 01 Jan 1990 00:00:00 GMT

when I switch to my Windows everything work (personal Gitlab and

I have the same issue. Firefox 81.0.1. Artix Linux (same Arch).

AFAIK it just happens at random. I don’t know if there is something I can tell to recreate the bug in other computer.
I tried so many things that I can bet I “refreshed” firefox a few times before posting the bug. (Refreshing firefox cleans add-ons, webstorage, cache, etc)
I’m currently using Gitlab from Chrome, i have no time to deal with it.

Running into this issue as well on Firefox 83.0 for Linux. Browser detection on the sign-in page crashes the tab.

Had same problem on fresh Manjaro on latest Firefox.
Solved by setting up correct system local datetime.

Had the same issue and now is fixed