Does anyone know how to fix this issue?
Magento 1.8.1
There has been an error processing your request
Can't retrieve entity config: core/store_group
Trace:
#0 /var/www/idfr/app/code/core/Mage/Core/Model/Resource.php(272): Mage::throwException('Can't retrieve ...')
#1 /var/www/idfr/app/code/core/Mage/Core/Model/Resource/Db/Abstract.php(284): Mage_Core_Model_Resource->getTableName('core/store_grou...')
#2 /var/www/idfr/app/code/core/Mage/Core/Model/Resource/Db/Abstract.php(247): Mage_Core_Model_Resource_Db_Abstract->getTable('store_group')
#3 /var/www/idfr/app/code/core/Mage/Core/Model/Resource/Db/Collection/Abstract.php(155): Mage_Core_Model_Resource_Db_Abstract->getMainTable()
#4 /var/www/idfr/app/code/core/Mage/Core/Model/Resource/Db/Collection/Abstract.php(192): Mage_Core_Model_Resource_Db_Collection_Abstract->getMainTable()
#5 /var/www/idfr/app/code/core/Mage/Core/Model/Resource/Db/Collection/Abstract.php(135): Mage_Core_Model_Resource_Db_Collection_Abstract->_initSelect()
#6 /var/www/idfr/app/code/core/Mage/Core/Model/Config.php(1348): Mage_Core_Model_Resource_Db_Collection_Abstract->__construct(Object(Mage_Core_Model_Resource_Store_Group))
#7 /var/www/idfr/app/code/core/Mage/Core/Model/Config.php(1380): Mage_Core_Model_Config->getModelInstance('core_resource/s...', Object(Mage_Core_Model_Resource_Store_Group))
#8 /var/www/idfr/app/Mage.php(491): Mage_Core_Model_Config->getResourceModelInstance('core/store_grou...', Object(Mage_Core_Model_Resource_Store_Group))
#9 /var/www/idfr/app/code/core/Mage/Core/Model/Abstract.php(208): Mage::getResourceModel('core/store_grou...', Object(Mage_Core_Model_Resource_Store_Group))
#10 /var/www/idfr/app/code/core/Mage/Core/Model/Abstract.php(213): Mage_Core_Model_Abstract->getResourceCollection()
#11 /var/www/idfr/app/code/core/Mage/Core/Model/App.php(613): Mage_Core_Model_Abstract->getCollection()
#12 /var/www/idfr/app/code/core/Mage/Core/Model/App.php(466): Mage_Core_Model_App->_initStores()
#13 /var/www/idfr/app/code/core/Mage/Core/Model/App.php(349): Mage_Core_Model_App->_initCurrentStore('', 'store')
#14 /var/www/idfr/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#15 /var/www/idfr/index.php(96): Mage::run('', 'store')
#16 {main}
