We have a site with Paypal pro configured as default payment processor.
One membership contribution page is linked to a webform (gathers additional contact data). Credit Cards details entered directly into the webform, are processed without a problem.
If a user opts to checkout via paypal the payment fails. The form attempts to connect to paypal.com but the error message
api_username Your purchase couldn't be completed Error Message
We cannot process this transaction because there is a problem with the PayPal email address supplied by the seller. Please contact the seller to resolve the problem. If this payment is for an eBay listing, you can contact the seller via the "Ask Seller a Question" link on the listing page. When you have the correct email address, payment can be made at www.paypal.com.
If I amend the payment processor settings in Civi and swap the api username, for the related account username, the paypal link works. payments can be processed.
Unfortunately other contribution pages (public donation pages) then fail to process payments.
After trial and error, we've identified that if you choose the paypal checkout button directly from the contribution page. A link like this is generated
If you follow the paypal checkout button from the webform the following link is generated
Does anyone know what may be causing two different links to be generated from the same underlying payment processor?
Is there any way of updating the webform so that the link to paypal comes out in the form https://www.paypal.com//cgi-bin/webscr?cmd=_express-checkout&token=EC-1154497557710463X#/checkout/login ?
My brain has melted trying to explain this as simply as possible. If anything is not clear. Please ask for clarification.