Online Store Saying Payment Method Temporarily Unavailable

[biggameink]

We've spent the last month building a Square website. But for the past few years, we've had our own website under another domain, but linked to Square to accept payments. It's worked fine until this week.

Customers are calling saying when they try & check out, they get an error that says "This payment method is temporarily unavailable. Error details: This request could not be authorized. Please choose another payment method."

Has anyone had this issue when they were transitioning from another site to a Square site? I'm thinking that maybe since we are building a new site, it's confusing something???