Mage_Backup is disabled after SUPEE-10975 patch or after upgrade to 1.9.4.0

Mage_Backup core module is disabled after SUPEE-10975 patch or after upgrade to 1.9.4.0. It is not possible to create Magento database backup as corresponding screen in backend is missing. Also it is not possible to use any third-party extensions that rely on Mage_Backup.

Cause

The backup module is disabled intentionally by patch/upgrade process.

Solution

If you wish to use Mage_Backup core module you can enable it with completing the following steps:

• change tag to true in app/etc/modules/Mage_All.xml for Mage_Backup module:
  

  --- app/etc/modules/Mage_All.xml
  +++ app/etc/modules/Mage_All.xml
  @@ -234,7 +234,7 @@
               
           
           
  -            false
  +            true
               core
               
                   
  

• in Magento Backend navigate to System > Configuration > Advanced > Disable Modules Output and change Mage_Backup option from disabled to enabled
• Flush Magento cache