Thank you @mprofile! That was immensely helpful. Looks like a typo in their .php file.
This happened to one of my sites also.
Thank you @simontpf for the suggestion to roll back to 6.2.2! This worked.
Interestingly, I didn’t even have time after manually rolling back to go and turn off the auto-update. It instantly updated to 6.3 again, but this time with no issue.
