Symptoms
The following error is shown on all pages or in report messages:
a:4:{i:0;s:47:"Cannot retrieve entity config: core/store_group";i:1;s:2039:"#0 app/code/core/Mage/Core/Model/Resource.php(161): Mage::throwException('Cannot retrieve...')
#1 app/code/core/Mage/Core/Model/Mysql4/Abstract.php(265): Mage_Core_Model_Resource->getTableName('core/store_grou...')
#2 app/code/core/Mage/Core/Model/Mysql4/Abstract.php(247): Mage_Core_Model_Mysql4_Abstract->getTable('store_group')
#3 app/code/core/Mage/Core/Model/Mysql4/Collection/Abstract.php(118): Mage_Core_Model_Mysql4_Abstract->getMainTable()
Cause
Cannot retrieve entity config: core/store_group error message means that default Magento configuration can not be inited on your installation.
It can happen if you accidentally moved/deleted files in app/code/core/Mage/Core directory, app/code/core/Mage/Core/Helper/etc for example.
Solution
- Check that app/code/core/Mage/Core/etc exists and is not corrupted. Check other files under app/code/core/Mage/Core or restore it from the backup or original Magento distribution.
- Flush Magento caches and disable Compiler (if it was enabled) or simply move includes directory out.
