Have you guys solved this issue? I tried registering for the Gre early in December 2019 but I ran into the same issue as you guys, then I came back home away from the US for my winter break and I tried registering for the GRE, I tried using a bunch of different credit cards, bank transfer, I tried different browsers and different computers as well and I just can't get past this god damn Error 481. Please let me know if you guys managed to solve this issue.