Every so often we keep getting the error:-
PHP Fatal error: Class 'Mage_Adminnotification_Helper_Data' not found in /var/www/vhosts/domain.co.uk/httpdocs/app/Mage.php on line 546
This causes the backend to produce a 500 Internal Server Error and the above error gets logged each time you try to access a URL in the backend.
Upon inspection though, everything in
app/code/core/Mage/AdminNotification is present and completely intact.
To fix the issue, I grab another copy of the above path from a working store and overwrite this one. Clear cache and then fixed, can access backend again.
I've run a compare between the
AdminNotification folder and all it's contents for the version that we replaced with and the version that was replaced. Every single thing in both folders are identical. Yet replacing with what was already there fixed the problem. Odd.
Is it possible that a 3rd party extension that serves inbox notifications in the backend could be the cause of this somehow? Maybe trying to extend this class incorrectly or something along those lines? Your advice/suggestions is greatly appreciated.