Site Restoration

#35898 Restoration Joomla 4 completed, but website gives error class Joomla\Plugin\System\AdminTools\Extension\AdminTools not found

Posted in ‘Site restoration’
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Environment Information

PHP version
CMS Type
CMS Version
Backup Tool Version
Kickstart version

Latest post by pwouda on Thursday, 30 September 2021 05:25 CDT


Hi there,

On localhost I created a Joomla 4 website from scratch, with Akkeeba Backup Pro and Akeeba Admintools Pro (both different download-id's). It works fine there, and the backup runs without problems.

Also the restore of the backup using kickstart on an online server, there are no problems.

When I want to open the website, or open the administrator-page, I get the error Class "Joomla\Plugin\System\AdminTools\Extension\AdminTools" not found

Thanks for checking this out.

Best regards,



Akeeba Staff


this is Joomla that is not updating the list of PHP classes for the installed extensions.

Please get inside the administrator/cache folder and delete the file autoload_psr4.php . Then open your site again, that should fix your issue.

Davide Tampellini

Developer and Support Staff

🇮🇹Italian: native 🇬🇧English: good • 🕐 My time zone is Europe / Rome (UTC +1)
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!


Thanks, that did the trick!

Best regards,

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