update to Big Sur made Apple Pay stop working

If you are getting a message that "Apple Pay has been disabled because the security settings of this Mac were modified" - go to Software Update/Advanced and uncheck the recheck "Install system data files and security updates." to see if that resolves the issue.

No it doesn't.

What error is it giving you? You have not provided very many details.

The exact same one as in https://support.apple.com/en-us/HT209016

List what you have done to troubleshoot the issue so far so I dont waste time repeating steps you tried.

First, apologies for my short post back there...it's been frustrating, and I should have been more clear up front.

I've done all the steps in the KB article - even gone beyond with extra reboots in between. SIP is enabled, and I even disabled the ability to boot from external devices. I've removed the eGPU and now run the monitors directly to the machine. Tried booting with nothing connected, everything connected, no difference.

No security settings changed when this triggered - there's no other users on the machine, and I work in cybersecurity and used used to help manage a mac environment with thousands of machines. This looks and feels like a bug introduced in 11.2.2.

The only thing I haven't done yet is to remove all the cards and set them up again - trying to avoid that because it's a PITA since it'll wipe them on all the devices.

Now on hold with Apple Support to get to Tier-2. Will report back if we can get it working.

Edit: Man do they have annoying hold music - high pitched piercing tones (and I picked 'silence' - tier-2 must have a different queue)

The hold music is "the worst!"

The following links could be helpful. Each link has the instructions in them once you click on them - About Secure Boot, Reset NVRAM or PRAM on your Mac, How to reset the SMC of your Mac

I was going to suggest signing out of your Apple ID and back in as well.

Ok, got it figured out. Root cause is that I created a bootable clone of my machine, booted to it, and enabled FileVault. In doing so, Big Sur moved the apple pay authorization to that external drive and disabled it on the internal one.

The fix is to delete one card, which will then trigger a prompt about the disk auth move, and ask you to reset apple pay. Do that, then re-enter the CCV's for all the cards, and then when that's done, the error will still be present. Reboot and it all works again.

In my defense I have no idea who makes bootable clones or not. I am glad you got it sorted.

I have a User Tip I created for Apple Pay issues and I added your resolution information to it. Problems and their solutions for Apple Pa… - Apple Community (scroll down to the Mac bits)