I have just changed my Hosting server and now are getting this error in my billing software where the credit card details should be shown. Fatal error: Call to undefined function: mcrypt_module_open() in /home/andmax/public_html/billing/encrypted/commonfunctions.php on line 603 Clientexec has sent this response: It is likely that you do not have mcrypt with curl ssl support compiled into your PHP. You must have your host re-compile PHP with mcrypt and curl ssl support in order to store credit cards in Clientexec. It is a requirement if you plan to use a merchant gateway such as Authorize.net, etc. Can anyone help me with this issue.