PayPal IPN "Internal Server Error" (v1.2.1)

Zen Cart 1.2.1
Patch: 1
Database Patch Level: 1.2.1

PHP Version 4.4.9

The thread found :here: said I should install 2 test scripts and post links to them. Both passed, but ipn.php (Apparently a file that in newer versions is replaced by ipn_main_handler.php) gives a 500 Internal Server error when accessed directly. Our client received an email from Paypal that IPN's were failing.

Here are links to the three files:
https://secure.j h s t u d i o s.net/~flowerte/ c u r l t e s t.php
https://secure.j h s t u d i o s.net/~flowerte/ i p n c h e c k.php
https://secure.j h s t u d i o s.net/~flowerte/ i p n.php

Zen Cart 1.2.1
Patch: 1
Database Patch Level: 1.2.1
Geesh!!!

UPGRADE

kobra:

Geesh!!!

UPGRADE

I dreaded that response.

This cart was built before I came into the company. It was built without overrides. It has been hatcheted and duck-taped together and I'd hate to undertake the project of upgrading it.

That being said, does anyone have an idea of what's going on?

I turned on debugging and recieved:
"... payment_status=Completed ..."

and on the customer's paypal account IPN history I get:
"Latest delivery attempt date/time8/22/2011 14:02 PDT
Notification URL https ://secure.j h s t u d i o s.net/~flowerte/ i p n.php
HTTP response code 200
Delivery status Sent
No. of retries 0"

Check this

http://www.zen-cart.com/forum/showthread.php?t=177771