If you recently had your Macbook Pro (Touch Bar) repaired (possibly with a logic board replacement), and restored from Time Machine backup, you might find yourself unable to use Apple Pay on Mac OS 10.12.5. The system will report “Apple Pay is already configured on this disk for another Mac” and ask you to “Reset Apple Pay and Add Card”. If you try to do so by authorizing it using fingerprint or password, it will immediately drop you back to the original “Apple Pay is already configured on this disk for another Mac” prompt, going back into this cycle ad infinitum.
The issue is that there is an Apple Pay cache at /private/var/db/applepay/ on the system that has been invalidated, but it seems to be unable to delete this cache properly. It will keep trying to refresh this cached data, and fail to do so.
There is a workaround for this. Obligatory warning: THIS IS MESSING WITH SYSTEM FILES. DO NOT EXECUTE ANY OF THIS IF YOU ARE NOT SURE WHAT YOU ARE DOING AND DO NOT HAVE A BACKUP OF YOUR DATA. TYPING THE COMMANDS WRONG MAY CAUSE SERIOUS ISSUES WITH YOUR MAC.
To fix this endless loop, you need to first clear out all the contents (but not the folders within) of the directories within /private/var/db/applepay/:
# get a root shell
# move the stale files away
mv /private/var/db/applepay/Library/Caches/* ~/.Trash/
mv /private/var/db/applepay/Library/Preferences/* ~/.Trash/
# kill the related cache servers
pkill seld; pkill ncfd;
– Wait a few seconds for the relevant servers to boot themselves up again. Then, go back to System Preferences, hit Add Card…
– It will fail the first time with a mysterious error. That’s fine. Hit Add Card again…
– On this second try, it will say “Apple Pay is already configured on this disk for another Mac”.
– When you hit “Reset Apple Pay and Add Card” for the final time, it will actually break past the loop, and you will get to re-enter your Apple Pay card information without further issue.
It’s a relatively easy fix, so I imagine the next OS version will have addressed this problem in a more elegant way.