I've been using PayPal Website Payments Standard for many years - I use both IPN and PDT. Recently I discovered that although IPN is still working fine, the customer is no longer returned to my website at the end of a purchase, so the PDT is not called, and the customer never makes it back to my website (this is new - it has been working fine for years).
I do have Auto Return turned on in my PayPal settings. The page it's supposed to go to exists and is working fine. That landing page is never hit in the logs.
This is broken on the live PayPal site and in the PayPal Sandbox. The page that I land on says "Your payment was completed. To continue shopping, please return to the merchant." There is no "Return to Merchant" button. The URL for this page is https://www.sandbox.paypal.com/webapps/hermes?flow=1-P&ulReturn=true&token=2GX255130M045604B&mfid=1540506852194_f375a853a7234&useraction=commit&country.x=US&locale.x=en_US&country.x=US&locale.x=en_US#/checkout/genericError?code=PAYMENT_ALREADY_DONE. This page used to automatically redirect back to my website.
On a related note (not sure if it's the same problem) the "Continue Shopping" button on the PayPal Cart page doesn't work anymore either. I am sending the URL for the page in a hidden field of the form I send to PayPal for my Add to Cart button as shopping_url, but when I click "Continue Shopping" it appears to be taking me Back (like a browser back) to the page that submitted the form rather than going to the page I specified in shopping_url. Again, this has worked for years, but now is no longer working.
Any help will be much appreciated!