From the upcoming release of CubeCart 5.2.6 we will no longer support Zend Optimizer or Zend Guard. Instead only Ioncube will be supported. It is crucial that you check that your server has Ioncube support before upgrading to 5.2.6.   Checking for Ioncube Support To check if Ioncube is available in your current hosting account configuration please login to the admin side of your store and navigate to "Advanced" >> "Server Info".    This will load a page which will show a great deal of