Error in configuration scope "default config" in General>Web

Question

When going to Default Config > Web I get the following error.

There has been an error processing your request

Invalid config field backend model: adminhtml/system_config_backend_web_secure_offloaderheader
Trace:
#0 /home/wengkomole/public_html/app/code/core/Mage/Adminhtml/Block/System/Config/Form.php(328): Mage::throwException('Invalid config ...')
#1 /home/wengkomole/public_html/app/code/core/Mage/Adminhtml/Block/System/Config/Form.php(229): Mage_Adminhtml_Block_System_Config_Form->initFields(Object(Varien_Data_Form_Element_Fieldset), Object(Mage_Core_Model_Config_Element), Object(Mage_Core_Model_Config_Element))
#2 /home/wengkomole/public_html/app/code/core/Mage/Adminhtml/Block/System/Config/Form.php(164): Mage_Adminhtml_Block_System_Config_Form->_initGroup(Object(Varien_Data_Form), Object(Mage_Core_Model_Config_Element), Object(Mage_Core_Model_Config_Element))
#3 /home/wengkomole/public_html/app/code/core/Mage/Adminhtml/Block/System/Config/Edit.php(92): Mage_Adminhtml_Block_System_Config_Form->initForm()
#4 /home/wengkomole/public_html/app/code/core/Mage/Adminhtml/controllers/System/ConfigController.php(107): Mage_Adminhtml_Block_System_Config_Edit->initForm()
#5 /home/wengkomole/public_html/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Adminhtml_System_ConfigController->editAction()
#6 /home/wengkomole/public_html/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(254): Mage_Core_Controller_Varien_Action->dispatch('edit')
#7 /home/wengkomole/public_html/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#8 /home/wengkomole/public_html/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()
#9 /home/wengkomole/public_html/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#10 /home/wengkomole/public_html/index.php(87): Mage::run('', 'store')
#11 {main}

On the other hand when selecting current configuration scope (Main Website) I don't get the error.

• MeenakshiSundaram R: seems like {magento-root}/app/code/core/Mage/Adminhtml/Model/System/Config/Backend/Web/Secure/Offloaderheader.php file is missing
• Kostas Panoulas: Thank you, but the above file does not exist in the Magento Version 1.9.0.1. Maybe another files is missing but I can not find which one.
• Kostas Panoulas: MeenakshiSundaram R, You were right. That file was missing. Thank you so much!

Answer 1

As per the comment

{magento-root}/app/code/core/Mage/Adminhtml/Model/System/Config/Backend/Web/Sec‌​ure/Offloaderheader.php

Above file is missing in your magento, so please copy the file from fresh magento and paste it in your system.