Opening System>Configuration>Catalog gives white screen

Question

When opening System>Configuration/Catalog I got an error message:

a:5:{i:0;s:87:"Invalid config field backend model: catalog/system_config_backend_catalog_category_flat";i:1;s:1660:"#0 /var/www/html/magento/app/code/core/Mage/Adminhtml/Block/System/Config/Form.php(328): Mage::throwException('Invalid config ...')

On further investigation the problem appeared to be that the file [magento directory]/app/code.core/Mage/Catalog/Model/System/Config/Backend/Catalog/Category/Flat.php didn't exist in my installation. I unzipped a fresh copy of the 1.9.0.1 installation elsewhere on the system and copied the file from there into my installation. P.S. this is the same version of Magento as I am using.

Now when I open System>Configuration>Catalog I don't get an error, but I can only see a white screen.

Not sure what to do next. Can anyone help?

[Update] Looked in /var/log/httpd/error_log and found this:

PHP Fatal error: Class 'Mage_Adminhtml_Block_Catalog_Form_Renderer_Config_DateFieldsOrder' not found in /var/www/html/magento/app/code/core/Mage/Core/Model/Layout.php on line 590, referer: https://www.somesite.com/index.php/admin/system_config/index/key/8adebffea188c0158e3fb1e303821fa4/

Answer 1

A white screen like this generally indicates a coding error, such as syntax, trying to call non-existent method. Have you looked in /var/log? The line in question will be indicated in there. I suspect you have just pushed the underlying issue downwards.

The bigger question is then why was the file missing. Check you have copied the file from the same version number exactly. It sounds like you might have other corrupt core files, maybe an upgrade gone wrong.

Answer 2

try this in you index.php:

Mage::setIsDeveloperMode(true);
ini_set('display_errors', 1);

you should see more details about the error