Please help i had encounter for my magento 1.9 with below error :
Trace:
#0 /home/tmsmy/public_html/shop.themarathonshop.com.my/app/Mage.php(223): Mage::throwException('Mage registry k...')
#1 /home/tmsmy/public_html/shop.themarathonshop.com.my/app/Mage.php(477): Mage::register('_singleton/athl...', false)
#2 /home/tmsmy/public_html/shop.themarathonshop.com.my/app/code/core/Mage/Adminhtml/Block/System/Config/Form.php(449): Mage::getSingleton('athlete/config_...')
#3 /home/tmsmy/public_html/shop.themarathonshop.com.my/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))
#4 /home/tmsmy/public_html/shop.themarathonshop.com.my/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))
#5 /home/tmsmy/public_html/shop.themarathonshop.com.my/app/code/core/Mage/Adminhtml/Block/System/Config/Edit.php(92): Mage_Adminhtml_Block_System_Config_Form->initForm()
#6 /home/tmsmy/public_html/shop.themarathonshop.com.my/app/code/core/Mage/Adminhtml/controllers/System/ConfigController.php(107): Mage_Adminhtml_Block_System_Config_Edit->initForm()
#7 /home/tmsmy/public_html/shop.themarathonshop.com.my/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Adminhtml_System_ConfigController->editAction()
#8 /home/tmsmy/public_html/shop.themarathonshop.com.my/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(254): Mage_Core_Controller_Varien_Action->dispatch('edit')
#9 /home/tmsmy/public_html/shop.themarathonshop.com.my/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#10 /home/tmsmy/public_html/shop.themarathonshop.com.my/app/code/core/Mage/Core/Model/App.php(365): Mage_Core_Controller_Varien_Front->dispatch()
#11 /home/tmsmy/public_html/shop.themarathonshop.com.my/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#12 /home/tmsmy/public_html/shop.themarathonshop.com.my/index.php(86): Mage::run('', 'store')
#13 {main}
