Clickbank IPN calls return 301 instead of 200

My site recently migrated from HostGator to WP Engine. We use the ClickBank shortcodes exclusively along with aWeber integration, but since the migration, the vast majority of purchases do not successfully update the membership, whether by directing the buyer to register or by updating existing membership. For the few orders that do proceed successfully to registration, almost none of their emails are added to aWeber.

Clickbank provided their entire IPN history for this account, and it appears that all of the post-migration IPN calls have been 301 redirected. Ran the Server Check Tool, and everything is fine there. Conversed with WP Engine Support; they don’t see anything on their end that should be causing this. In fact, their cURL output for the IPN URL is 200 OK.

The Clickbank IPN log shows the widely-cited “Unable to verify $_POST vars” error message for each order. While this was also showing up pre-migration, at that time the message was immediately followed by the array containing the transaction details. This is no longer the case; it’s just the message now, every time. As for the return logs, everything looks normal.

The various API keys are correct, as are the IPN and thank-you URLs in Clickbank and the list servers in aWeber.

On a possibly related note, the plugin has on at least two occasions completely reset itself to “factory” settings for no apparent reason. Each time, I’ve had to rely on database backups to piece everything back together.

That’s everything I can think of. Bottom line: Why aren’t these memberships being added/updated properly?

Thanks for your inquiry. ~ We appreciate your patience :-)

My site recently migrated from HostGator to WP Engine.

The Clickbank IPN log shows the widely-cited “Unable to verify $_POST vars” error message for each order.

Did you also change domain names?
Did your s2Member® Security Encryption Key change?
See: Dashboard -› s2Member® -› General Options -› Security Encryption Key

Please submit a Dashboard login and we’ll inspect your log files for the underlying issue. Thanks!
Please use: s2Member® » Private Contact Form

Details received. Thank you!

I see several entries in your clickbank-ipn.log file where this variable is completely empty.

'cvendthru' => '',

This would indicate to me that your ClickBank Button was not implemented with an s2Member® Shortcode? In other words, it appears that you are missing all of the s2 Vars that should be passed through ClickBank so that s2Member can handle post-processing for you.

See: Dashboard -› s2Member® -› ClickBank® Buttons -› s2 Vars (Explained)
See also: http://www.s2member.com/forums/topic/using-clickbank-and-paypal/#post-11438

Please let us know if problems persist :-)

Shortcodes are in place across the board. Here is an example:

[s2Member-Pro-ClickBank-Button cbp="15" level="1" ccaps="plat" desc="Platinum Package Lifetime" custom="***DOMAIN***" tp="0" tt="D" rp="1" rt="L" rr="0" image="http://***DOMAIN***/wp-content/themes/OptimizePress/images/large-addtocartg.png" output="anchor" /]

And as for ‘cvendthru’, those entries all took place prior to migration. In fact, it seems as if the log stopped adding new entries some time ago, which makes it impossible to know what, if anything, has changed.