After changing the backend name... error 500

[Borislav Georgiev]

Hello, after changing the name of the folder for the administrative interface, I no longer have access to the entire website. I'm getting a 500 error through the browser. The Apache logs say the following:

AH01071: Got error 'PHP message: PHP Fatal error: Uncaught Error: Call to undefined method Configuration::getMultiShopValues() in WEBSITEFOLDER/classes/shop/Shop.php:398\nStack trace:\n#0 WEBSITEFOLDER/config/config.inc.php(117): ShopCore::initialize()\n#1 WEBSITEFOLDER/index.php(27): require('...')\n#2 {main}\n thrown in WEBSITEFOLDER/classes/shop/Shop.php on line 398'

I am using PrestaShop 8.1.2, PHP 8.1, MariaDB 10.11. Could you help me with resolving the issue? I am new to PrestaShop and web programming in general, still in the learning process.

[musicmaster]

Most likely a caching issue. Try deleting the /var/cache directory. 

[Borislav Georgiev]

It turned out that the issue was not with Prestashop. Since I use the Plesk control panel, during that time, I installed an extension that automatically changed the entire configuration of PHP and Apache. After restoring the configuration, everything is working fine.