I am getting this error in my payment gateway. When my clients are getting their invoice details meaning after payment transaction they are seeing this error. Please help me because I am very new in gateway integration coding. I am using MCRYPT_RIJNDAEL_128 and mode is MCRYPT_MODE_CBC.
Are you using an old version of VirtueMart - see http://forum.virtuemart.net/index.php?topic=79799.0