Error when accessing admin after install

I've just installed the "Pearl Theme for Magento 2 Commerce - Professional Pack" (Version 1.10.15).

Right after, I can't access admin.

The debug.log shows :

[2021-09-07 09:35:22] main.CRITICAL: Specified invalid parent id (WeltPixel_Backend::WeltPixel) {"exception":"[object] (OutOfRangeException(code: 0): Specified invalid parent id (WeltPixel_Backend::WeltPixel) at /var/www/html/magento242-demo/vendor/magento/module-backend/Model/Menu/Builder.php:83)"} []
[2021-09-07 09:35:22] main.ERROR: Specified invalid parent id (WeltPixel_Backend::WeltPixel) [] []
[2021-09-07 09:35:22] main.CRITICAL: Specified invalid parent id (WeltPixel_Backend::WeltPixel) {"report_id":"7cfd75936957459fafdf6efa08aa216d1e40d28182b9f5e40cf6bd4d894d60cf","exception":"[object] (OutOfRangeException(code: 0): Specified invalid parent id (WeltPixel_Backend::WeltPixel) at /var/www/html/magento242-demo/vendor/magento/module-backend/Model/Menu/Builder.php:83)"} []

I'm using Magento 2.4.2 with demo data.

Any hint to solve this problem ?