I fear not. With http3 enabled, the auto-updater never returns a result. It keeps saying "checking...". Looks like the auto-updater itself will work only when http3 is disabled through about:config which non-technical people may not be able to do.

However I do recall Mozilla having another backdoor channel which they used sometime ago to push an emergency update. I hope that works.

Someone just reported that it looks like a load balancer issue. Presumably, if that's the case it can also be fixed without user action: https://bugzilla.mozilla.org/show_bug.cgi?id=1749908#c17

I hope i am mistaken, but the auto-updater of my own FF was blocked.

Exactly what I was thinking. I hope they thought about this case and made the updater use a different stack...

Several non techie friends already contacted me about a broken FF. There will be millions of people with this problem, indeed.

I can confirm auto-updater got broken too. When I realized my browser (nightly) was borked, first instinct was to update.. but nope, that didn't work. Then I manually downloaded a new nightly tarball, but that also didn't help. Switched to stable (95.0.2) and that worked once, then it got borked too.

Was blocked on my machine too, but spontaneously started working again after a complete reboot without the disable http3 fix, so there is hope! :D