error when customers try to pay invoice

Description

I have sent out 2 invoices to 2 different customers and all looks good on my end, but when they click the link to go and pay it, they receive an error stating: « Something went wrong on our end. We are sorry, we’re having some trouble completing your request right now. Please try again shortly. »
I sent the first invoice out 3 days ago, and the second one today and both received the same errors.
Ive sent out invoices before and they’ve been paid without any issues.. does anyone know whats going on?? i need this fixed asap and am stressing