I have been experiencing this weird issue the last 2 weeks, and it's happening very randomly.
- customers were using IE as the browser
- they put something in the shopping cart and clicked PayPal Express Checkout
- they were redirected to PayPal, logged in, and clicked to come back to my site to confirm the order
- then they saw an error message that says Unable to initialize Express Checkout (at this stage, this order actually got through, payment processed and Magento order created)
- thinking that the order did not get through, they retried, and failed, and finally gave up by using the normal PayPal checkout, which worked.
- they then saw duplicate payments in PayPal and sent me complaints
Could anyone please guide me in the right direction?