I just updated to 5.4.1 to be safe, per the recommendation that came through on my support ticket. I pushed through another test, and it still seems to be working fine. I’ll reply back if we have any more errors reported.
It seems to be intermittent? I tested with a credit card (after a customer reported the same error) around 10 or 11, and it gave me the error. After returning from lunch around noon I saw that an order had come through successfully so I tested again (with the same credit card) and it worked fine.
I’m still curious about what caused the issue in the first place. We hadn’t made any major changes on our end before OR after experiencing the issue.
Yes! We just started having this same issue today. We also use Authorize.net to process payments. Please reply if you figure out a fix.