Fatal error: Uncaught Error: Call to undefined function get_user_by() in /home/www/guennyairbrush.de/wp-includes/user.php:1984 Stack trace: #0 /home/www/guennyairbrush.de/wp-includes/version.php(114): username_exists('root') #1 /home/www/guennyairbrush.de/wp-content/plugins/updraftplus/class-updraftplus.php(901): include('/home/www/guenn...') #2 /home/www/guennyairbrush.de/wp-content/plugins/updraftplus/class-updraftplus.php(155): UpdraftPlus->get_wordpress_version() #3 /home/www/guennyairbrush.de/wp-content/plugins/updraftplus/updraftplus.php(233): UpdraftPlus->__construct() #4 /home/www/guennyairbrush.de/wp-settings.php(526): include_once('/home/www/guenn...') #5 /home/www/guennyairbrush.de/wp-config.php(117): require_once('/home/www/guenn...') #6 /home/www/guennyairbrush.de/wp-load.php(50): require_once('/home/www/guenn...') #7 /home/www/guennyairbrush.de/wp-blog-header.php(13): require_once('/home/www/guenn...') #8 /home/www/guennyairbrush.de/index.php(17): require('/home/www/guenn...') #9 {main} thrown in /home/www/guennyairbrush.de/wp-includes/user.php on line 1984