Note: This is a historical reference, not a current security baseline. Magento 1 is end-of-life.

Problem description

The following PHP fatal error message appears on attempt to open Magento Backend after SUPEE-5344 patch installation: Call to undefined method Mage_Core_Controller_Request_Http::getInternallyForwarded() in app/code/core/Mage/Admin/Model/Observer.php on line 76

Cause

getInternallyForwarded method is introduced in SUPEE-5344 patch. According to the error message it is referred in code, however Magento can not find its definition. It means that
  • either SUPEE-5344 was not applied fully and app/code/core/Mage/Core/Controller/Request/Http.php file still contains unpatched code
  • or old code is still running from compiled caches

Solution

  • Ensure that app/code/core/Mage/Core/Controller/Request/Http.php file was updated properly and contains getInternallyForwarded function, it exists only in patched file. You can get this file for your Magento version here
  • Disable Magento Compiler and clear compiled code as shown in this article
  • Flush PHP opcode cache by restarting webserver, or request your hosting support to flush PHP opcode cache