Just this month of April I have had this issue. Once my customers press buy it now for the PayPal/Credit Card option they are taken to PayPal website checkout but this message is popping up all the time.

Things don't appear to be working at the moment. Please try again later.

My online site has been in operation over 5 years and never had this issue until now. Called Paypal and they claim that the problem is with the code for my buy it now button. This code is automatically done by the software Website X5. My version is 11.0.8.31

I would gratefully appreciate all the help from anyone.

Thanks