The PayPal endpoint for credit card payments in the web does not gracefully handle connection timeouts. PayPal transactions would complete on the provider side but would sometimes not be updated in Aeon. Logs indicate that a connection timeout when trying to post back to PayPal in CompletePayPalIPNPayment raises an uncaught exception.
Bug# 53600 votes
The button should disable itself when clicked until we've received a response from the Aeon server or otherwise timed out.
If the billing amount is 0, it is not halting the process. You can't click a button until there is a value for the transaction number or the billing amount.
Bug# 56380 votes