I've installed Magento 2.3.4 on xampp 7.2.28-0. The admin-panel didn't load so i started researching and did the following: go to: /vendor/magento/framework/View/Element/Template/File/Validator.php
$realPath = $this->fileDriver->getRealPath($path);
$realPath = str_replace('\\', '/', $this->fileDriver->getRealPath($path));
After this I could log in but the Admin-Panel didn't load and the logos didn't show.