Bug: Unable to login into this forum via Firefox

[thoste]

At first I tried to login into this forum via newest Firefox on Windows.

This is not possible.

A login popup with rotating circle appears which rotates forever.

Whats wrong?

I had to use Chrome for this post.

[Maksym Kozub]

I am writing this using Firefox 91.5.1esr, and I had no problem with logging in.
Did you try starting your Firefox with all extensions disabled?

[eumagga0x2a]

Just FYI, at least in order to be able to download attachments, I have to set network.http.spdy.enabled.http2 to false when using Firefox, which means that in browsers where I cannot disable HTTP2 like in Safari, I cannot download attachments here at all

But login, indeed, works fine for me, even with HTTP2.