Akeeba Backup for Joomla!

#36819 Class 'Joomla\Plugin\System\BackupOnUpdate\Extension\BackupOnUpdate' not found

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Environment Information

Joomla! version
PHP version
Akeeba Backup version


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Description of my issue:

Installed Backup Pro to fresh install Joomla 4.1. Extension says it has installed correctly, but when trying to open Control Panel (or any other menu item) I receive:

Class 'Joomla\Plugin\System\BackupOnUpdate\Extension\BackupOnUpdate' not found

Akeeba Staff

Delete the file administrator/cache/autoload_psr4.php.

You should do that every time you get a Class Not Found error after installing or updating ANY extension. This file is supposed to be generated by Joomla every time you install or update an extension, it's Joomla's cache of where to find each extension's files. If it's out of date you will get Class Not Found errors on your site. If the file is missing it will be automatically regenerated in the next page load from the information in the XML files of installed extensions.

Nicholas K. Dionysopoulos

Lead Developer and Director

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Thank you. Worked perfectly.

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