Magento Compiler feature should be disabled on any changes in loaded Magento classes, in other words, you need to disable Magento Compilation every time before installing new extension or initiating upgrade/downgrade/installation or removal of any Magento module.
To disable Magento Compiler you can use one of the following methods:
Admin Interface
- navigate to System > Tools > Compilation page and click on Disable button:
Console/SSH
- Check current compilation status
$ php -f shell/compiler.php -- state Compiler Status: Enabled Compilation State: Compiled Collected Files Count: 6042 Compiled Scopes Count: 4
- Disable Magento compilation:
$ php -f shell/compiler.php -- disable Compiler include path disabled<
- Clear all compiled files
$ php -f shell/compiler.php -- clear Compilation successfully cleared
- Ensure that compiler is disabled now by checking its status:
$ php -f shell/compiler.php -- state Compiler Status: Disabled Compilation State: Not Compiled Collected Files Count: 0 Compiled Scopes Count: 0
FTP/Filemanager
- delete includes directory or rename it to any other name (_includes.unused for example):
ftp :~> mv ./includes ./includes.unused
Then Flush Magento cache.