Apple Pay Crashing Safari - Unable to add new cards

Okay, I might have figured out a way to solve this problem. I hope it works for others.

1. Go to iCloud and delete all cards from all devices that have Apple Pay configured. Every device on the Device list must show no Apple Pay icon.

2. Go to your iPhone, Watch, MacBook Pro, and delete any cards still existing on Apple Pay. Make sure none are configured, neither on the devices nor on iCloud.

3. Wait a few hours (I waited overnight) because iCloud apparently takes a while to refresh and delete all cards setup on Apple Pay.

4. The next day, I went to Safari - Preferences - Privacy - Delete all website data

After step 3 I was, once again, able to go to Mac OS Preferences, Wallet & Apple Pay and add new cards (without the Preferences pane crashing on me). After step 4, Safari's preferences pane started opening with no major delays and the Privacy menu also started showing quickly.

For a moment I thought I might have to reinstall Mac OS, get a new Mac (this one is 15 days old), or some other time-consuming task like that. This seems to have solved the problem and I hope it can help somebody else.

Cheers.

Update on the issue:

Apple Care escalated the issue and asked for my permission to look into my Apple ID. This took 48 hours, by the end of which I was told that the Apple Server is fine, so the problem lies in the hardware (i.e. my MacBook Pro); I was advised to take it back to the Apple Shop and get a replacement, which I did today. I'll update this forum again once I've set up the new MacBook Pro - hopefully the issue has gone now.

I found a simpler solution to this problem. Simply clear the pram on your MacBook. Reboot while holding option-command-p-r and you should be able to add cards to Apple Pay with no problems.

Reset NVRAM or PRAM on your Mac - Apple Support

Just to add one more thing: we've also tried removing the linked Apple Pay credit card from iCloud as well as removing the computer from the associated Apple ID - nothing worked. The linked card under Apple Pay on this MacBook Pro can't be removed - it keeps saying 'Apple Pay - pending deletion', despite having received an email from the card issuer confirming the card has been removed.

The problem seems to be a glitch that's preventing card deletion in iCloud. I will update this forum as soon as I've heard back from Apple Care.

I have the exact same problem. Spent hours with Apple Care, who are still looking into it.

We've tried all the usual stuff - logging in and out of iCloud, removing the MacBook Pro from iCloud, etc. We even tried setting up a different user account to check if it's the computer or something to do with Apple ID. Still no luck.

I'll update the forum here when/if I hear of anything from Apple Care.

I am experiencing the same problem on Wallet & Apple Pay under System Preferences. Also, when I go to Safari - Preferences it appears to freeze and after a while Safari's preferences appear. With Wallet and Apple Pay, however, it just crashes and I must Force Quit the System Preferences menu.

Exactly the same is happening to me. Not sure how to work around it. Pretty crappy experience on my brand new MacBook Pro!

I tried your solution and was able to TRY and add a card, however after entering card details it just reported back that the card was already in Wallet...

Logged into the AppleID site and sure enough it was still linked to my MBP. I'll try again morrow just in case it's an iCloud issue.