Fatal error: Uncaught Error: Call to undefined function get_user_by() in /var/www/html/wp-includes/user.php:1984 Stack trace: #0 /var/www/html/wp-includes/version.php(114): username_exists('root') #1 /var/www/html/wp-content/plugins/health-check/compat.php(4): include('/var/www/html/w...') #2 /var/www/html/wp-content/plugins/health-check/health-check.php(36): require_once('/var/www/html/w...') #3 /var/www/html/wp-settings.php(471): include_once('/var/www/html/w...') #4 /var/www/html/wp-config.php(112): require_once('/var/www/html/w...') #5 /var/www/html/wp-load.php(50): require_once('/var/www/html/w...') #6 /var/www/html/wp-blog-header.php(13): require_once('/var/www/html/w...') #7 /var/www/html/index.php(19): require('/var/www/html/w...') #8 {main} thrown in /var/www/html/wp-includes/user.php on line 1984