If you're receiving an Unexpected Error message while trying to add a Merch Card, this tyipcally means that the YouTube API request has timed out. If you wait about 10-15 minutes and try adding the Merch Card again, it should work.
If you're receiving an Unexpected Error message while trying to add a Merch Card, this tyipcally means that the YouTube API request has timed out. If you wait about 10-15 minutes and try adding the Merch Card again, it should work.