2CheckOut

Callback Setup

To setup the callback process for 2CheckOut to automatically mark invoices paid, go to the Account > Site Management section in the 2CO Vendor Admin and set "Direct Return" to "Given links back to my website" and the "Approved URL" to http://www.yourdomain.com/whmcs/modules/gateways/callback/2checkout.php

Secret Word

For added security, on the same page you can set a "Secret Word". If you set this, in the payment gateway configuration page of your WHMCS system, enter the same secret word so that WHMCS can verify that the callbacks it receives are coming from 2CheckOut.

API Username/Password

You can set your 2CheckOut API username & password in these fields if you wish to be able to automatically process refunds from WHMCS. These fields are optional and can be left blank.

Error Messages

Test Mode Limitation

Please note when using demo mode, that all callbacks will fail with the error MD5 Hash Failure if a secret word is specified. This is done intentionally by 2Checkout to protect those who sell digital goods from fraudulent purchases through the demo mode.

MD5 Hash Failure

A MD5 Hash Failure error under Billing > Gateway Log indicates that the Secret Word in Setup > Payment Gateways does not match the Secret Word in the 2CheckOut control panel. They must match exactly.