Cannot reach login page with nginx reverse proxy basic auth

Hi everyone.
I’m experiencing a strange problem with login page. Different behaviour exists when i use firefox and chromium. With FF no problem, but with chromium yes.

My xwiki setup is the following:

nginx reverse proxy + basic auth —> xwiki

So when i connect to xwiki main page the authentication prompt of nginx appears and I can “log in with nginx credentials” and display without problem the home page. But when i try to reach the login page a blank page is shown. I debugged a little through the network console and i saw that my request to login page return http 401 error. I noticed that is the default response code returned by page when unauthenticated user try to login, but i think that this can broke whole authentication process started with nginx basic auth. In fact if i try to reload the page the authentication prompt of nginx appears again.

How can i solve this issue?

Thanks in advance