Hi,
We have our store setup with PayPal standard payment. Each time a user completes a payment and is taken back to our site he/she will see a red error message saying:
“Your order has been declined by the payment processor. Please review your information and contact store administration.”
This error message is showing incorrectly since the user payment was received correctly. Looking at the cs-cart control panel the order is marked as Complete, so this doesn’t seem to be the cause for this issue either.
This issue happened at some point in the past and resolved itself after a while (I wish I knew how??), but started again for the past day or two. We’ve been spending ours trying to figure out what might be causing this without any luck 
I would really appreciate any peace or advice anyone might have here! I’m completely lost and hopeless at this stage.
Many thanks!
-A-
New orders never go to Complete status on their own in the standard cart. So it looks like you might have something else (3rd party addon maybe) going on that is hooking into the fn_finish_payment() function.
I think most problems stem from incorrect settings in PayPal.?
Thanks guys for the follow-up and help!
I went ahead and verified our configuration on PayPal side compared to the requirements listed with CS-Cart. According to the details here: CS-Cart Documentation — CS-Cart 4.15.x documentation
Our PayPal configuration had IPN enabled, but it was enabled due to a different system since we sell our apps also directly via our Android and iPhone apps where we use PayPal InApp purchase - so the IPN was applied only to process orders arriving from our InApp implementation. To be sure this isn't causing this problem I disabled IPN completely for the sake of testing.
We also had “Auto Return for Website Payments” enabled and configured to take the user back to our site where he/she will be displayed with the Complete.tpl content along with their registration information details. I also disabled this feature - although it feels very weird requirement since now the user isn't taken back to our site after the payment is completed.
After making this changes and making sure the PayPal configuration follows CS-Cart settings I tried to perform two additional test orders, the first with sandbox and the second with real production PayPal account. In both cases I received back the same usual error. 
I've also attached a capture showing the error we're getting, in case anyone might be familiar with this error message.
As far as I can tell, we haven't installed any add-on or hook. The store was also working nicely for a while and it seems this issue started at some point without any exact reason that I can point.
If you need me to check anything in the code/mysql let me know, any advice or direction will be very helpful!
Thanks!
PayPal standard is all I use and I have never encountered the issue. If you are using the latest version (2.2.1), I suppose it could be a bug.