Magento Version 1.9.0.1

Admin System Configuration Design Error

This a problem existed during a new installation.

Although everything seemed fine during the installation of a new theme I encounter the dreaded: “There was a problem processing your request” screen.
This was found to be a ‘cache’ issue and the fix is shown below.

Locate the following file.

[Magento root]/lib/Zend/Cache/Backend/File.php

In the file change the following line:

‘cache_dir’ => null,

To

‘cache_dir’ => “var/tmp/”,

You must then create a folder and assign write chmod permission 666:

[Magento root]/var/tmp

Image of where to change the setting