Have just updated development site from 4.039 to 5.018 via online update process (been on 4.039 for 2 years - no problems). Using Payments Standard
Tested on sandbox - all appears ok on sandbox. Both the seller and buyer pp accounts are updated with the transaction.
However the buyer isn't returned to the checkout success page but back to the shopping cart via checkout_process with an alert Could not verify the PayPal transaction. Please try again
Order remains Preparing [PayPal Standard]. No emails are sent (obviously).
Running on standard 2.3.4 - updated to run on php 7.0.33 (deprecated constructor issue) and updated to use bootstrap. (Separate install issue - noticed that some files in this PayPal online update have not been updated for the constructor issue)
Scratching my head on this one.
I have attached xlsx with relevant server log and paypal log.
Any ideas where to start?
5.018 paypal sandbox test.xlsx