The Facebook app isn't working on my iPhone

Apple released a Rapid Security Response on Monday that proved to be buggy. They pulled it almost immediately because it made it caused problems with accessing some web sites including Facebook. See:

If you applied Rapid Security Response iOS 16.5.1 (a), iPadOS 16.5.1 (a), or macOS Ventura 13.4.1 (a) - Apple Support

and this Arstechnica article:

https://arstechnica.com/security/2023/07/apple-releases-quickly-pulls-rapid-security-response-update-for-0-day-webkit-bug/

Remove the bad file using instruction in that article. The repalced, version (c) was relased Thursdays and I have hed no issues with it.

Have you contacted Facebook ?

I have contacted Facebook, they told me to contact ios developers cause they have a lot users facing the same issue since last software update.

change wifi server and connection error.check facebook update.

Hello 3zo3zo!

If you’re having issues with third party apps, please contact the developer/s of them for further assistance.

In this case, try following the on-screen instructions.

I hope this is helpful. Good Luck!

I am having the same issue, did you solve it??