Same problem here, began immediately after booting and updating to 150. Other websites running normally. Cleared history and cache, currently in troubleshooting mode, but no Facebook. Just a blank page.

Thank you both and reporting, we are tracking the issue here: https://github.com/webcompat/web-bugs/issues/217280

Hack that worked for me:

Open about:config, search for security.tls.version.max and change it from 4 to 3.

WARNING from the moderator team: Changing Firefox preferences from the about:config page can sometimes break Firefox or cause strange behavior. You should only do this if you know what you're doing. Please read Firefox advanced customization and configuration options to learn more.

Just tried that and yes it does solve my problem. No idea why though.

Because something sitting between the browser and Facebook's delivery edge doesn't like the connection using the most modern protocols — while using a fallback one connects correctly. (Flipping this pref basically disables some necessary prerequisites right away for the HTTP/3 to even happen.)

Is it possible that you use some antivirus or security software, like Bitdefender?

I do indeed use Bitdefender, but that doesn't explain why Facebook always worked well until that time in the afternoon when Firefox updated to 150 and why it continued to work with other browsers with no problem. But the small change suggested above did solve the problem, so it must be a change in Firefox that caused the problem.

Hi all, this issue should be resolved with the next Firefox update. Meanwhile, disabling BitDefender or turning off its traffic filtering features may help.

For reference, see bug 2034178 (particularly, this comment). Long story short, an implementation of a new HTTP/3 feature was introduced in v150, which BitDefender wasn't ready for. As a result, BitDefender's traffic filtering corrupts server responses that use this feature (which is the case with Facebook).

I'm sorry, but I really don't see turning off my virus protection as a safe way to solve this problem. The suggestion by dbert721 above has solved the issue for the moment.

Confirming @Denys' reply 4/24/26 5:55pm

I run Bitdefender. I added www.facebook.com to: Bitdefender > Protection > Antivirus > Settings > Manage exceptions > +Add an Exception

This solved the problem for me. I did not have to disable any of Firefox extensions that I had running.

Like @brianlec I don't like turning off the virus protection. Hopefully the issue will be fixed soon.

Hi folks,

Just noting that this issue will be fixed in the upcoming Firefox version 150.0.1. If you flipped the security.tls.version.max value from about:config, I'd suggest to return it back to the original value once you updated to 150.0.1.

@ PMac53, does this then exempt Facebook for any virus protection?

Hi folks,

Just a reminder that Firefox 150.0.1 is coming out today.

Those of you who went to change any security settings to work around the connection issues, please don't forget to go back and set them back to their previous values once you're updated to the latest Firefox version — so that you get back the speed and security features they are responsible for.