OMG - Apple is intentionally blocking Firefox!

I changed Firefox useragent using "User-Agent Switcher and Manager" to Safari 11.0 and iOS 11.3 and then I was able to login.

And people wonder why Firefox market share is so low. It obviously isn't. It's just that we are forced to cloak it so that we can get work done.

But this is really petty of Apple to do - really petty!

Corresponding thread in Apple support https://discussions.apple.com/thread/256123073

Changing the user agent is indeed the fix here. Interestingly, not much needs to be changed. It doesn't seem to be an issue Apple has with Firefox/Mozilla, but Ubuntu.

The user agent I had was: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:142.0) Gecko/20100101 Firefox/142.0

I changed it to the following to make it work: Mozilla/5.0 (X11; Linux x86_64; rv:142.0) Gecko/20100101 Firefox/142.0

In other words, all I did was delete "Ubuntu."

You can use the add-on mentioned to do this, or you can do this much more simply:

1. Type about:config in the address bar
2. Search for the preference general.useragent.override
3. Add or modify the preference to a string containing the user agent

I used this to login and then deleted it so that it wouldn't cause other problems.

Having the same problem for two days on icloud.com and account.apple.com (also on Ubuntu 24.04.3 LTS, latest Firefox). I am temporarily using Brave now. Not ideal but at least I have accesss now. Mozzilla please fix this!