Upgrade to 8.1 from 7.7.1

[executable77]

Hello,

 

I'm getting some trouble to update my WHMCS to the latest version (8.1). I tried to update it in manual way (cli) and using the update wizard (browser). I have always the same error.

WHMCS is configured on PHP 7.4 and on nginx using php-fpm.

When the update is completed I'm able to navigate to the admin area but i can't navigate on the client side.

 

Here is the error I'm getting :

2021/04/23 16:21:36 [error] 16656#0: *203 FastCGI sent in stderr: "PHP message: [WHMCS Application] ERROR: TypeError: Argument 1 passed to Knp\Menu\MenuFactory::createItem() must be of the type string, null given, called in /usr/share/nginx/html/vendor/whmcs/whmcs-foundation/lib/View/Menu/MenuFactory.php on line 0 and defined in /usr/share/nginx/html/vendor/knplabs/knp-menu/src/Knp/Menu/MenuFactory.php:28 Stack trace: #0 /usr/share/nginx/html/vendor/whmcs/whmcs-foundation/lib/View/Menu/MenuFactory.php(0): Knp\Menu\MenuFactory->createItem() #1 /usr/share/nginx/html/vendor/knplabs/knp-menu/src/Knp/Menu/MenuItem.php(356): WHMCS\View\Menu\MenuFactory->createItem() #2 /usr/share/nginx/html/vendor/whmcs/whmcs-foundation/lib/View/Menu/Item.php(0): Knp\Menu\MenuItem->addChild() #3 /usr/share/nginx/html/includes/hooks/sidebar.php(114): WHMCS\View\Menu\Item->addChild() #4 /usr/share/nginx/html/vendor/whmcs/whmcs-foundation/lib/Hook/Manager.php(0): WHMCS\Utility\SafeInclude::{closure}() #5 /usr/share/nginx/html/vendor/illuminate/support/Facades/Facade.php(261): WHMCS\Hook\M" while reading response header from upstream, client: 58.24.14.2, server: www.example.com, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/var/run/php-fpm/php-fpm.sock:", host: "www.example.com"

Thanks for any help,

Cheers