Akeeba Backup English discussion

This topic discusses the backup system for Joomla! Akeeba backup.

Probably everyone with Joomla installed has Akeeba Backup. When upgrading to Joomla! 4.1 there is a message about the impossibility of updating.
"FEF is no longer needed in Joomla 4
Summary: FEF is no longer used in Joomla 4. Please remove it.
Akeeba FEF, also known as Akeeba Front-End Framework, was a CSS and JavaScript framework used by Akeeba Ltd with the Joomla 3 versions of our software.
Akeeba Ltd has stopped using the FEF platform for extension development. All of our extensions have new native versions of Joomla 4 that use the Bootstrap library included with Joomla 4 itself.
You can no longer install or update FEF on Joomla 4.1 and above (you have 4.1.0). Actually, you just need to remove it.
Extension: Update: Error in custom install script.
FOF is no longer needed in Joomla 4
Summary: FOF is no longer used in Joomla 4. Please remove it.
FOF, also known as Framework-on-Framework, was an extension development framework used by Akeeba Ltd (and some third-party extensions developed by companies not affiliated with Akeeba Ltd) for Joomla 1.5–3.10.
Akeeba Ltd has stopped using the FOF platform for extension development. All of our extensions have new native versions of Joomla 4 that use the Joomla Core MVC library included with Joomla 4 itself.
You can no longer install or update FOF on Joomla 4.1 and above (you have 4.1.0). In fact, you just need to remove it.".

After deleting FEF is no longer needed on Joomla 4 and FOF gives an error Class "FOF40\Container\Container" not found, without the ability to enter the admin panel.
Solved by deleting the plugins/system/backuponupdate folder.