Can't Download 24H2 Because of Antivirus?

So in early January I decided "the hell with it" and tried to download the new version of Windows 11 on a year-old PC (AMD Ryzen 7 5700G with Radeon Graphics), but during the reboot process it gave me the :( message and said they had a problem. It said it would reboot my PC automatically but that didn't happen and I had to power off and restart, which went fine.

On the Update thing it said they couldn't download it, and gave the error code that indicates it's either an old driver (unlikely- I just bought this in April 2024) or my antivirus (Bitdefender). I was going to try again later... but then the option to get the new version disappeared! The button is no longer there!

I generally wait several weeks before downloading the new Windows Updates as it is, but where did the button to try downloading it go? And... do I REALLY need to uninstall Bitdefender just to download an update? That seems ridiculous and over-complicated.

I might just bring it into a shop to get it done; I'm not computer literate enough to go through the hassle of messing around with functions and uninstalling/reinstalling stuff. Can Microsoft not fix this, or is this possibly a one-time problem?