After successful login, page stays on login form

I recently updated our main project from 2025.6 to 2025.9, and now the login form is behaving strangely:
when we enter the username/password and choose login, the login will show progress, but then remains on the login screen. even if we do multiple times, but it is enough to refresh the page (F5) to have the application load correctly.

as if there login occurred but the page didn’t refresh. What’s the issue? Anybody have such issue?

I cannot reproduce the issue. You should enable Debug to check the error in more detail.

Seems a configuration issue but I cannot fix it yet:
on my local webserver it works fine, but on the main webserver it doesn’t.

When I enable Debug login doesn’t even work, gives error messages, I have to investigate more