Fatal error: Uncaught Error: Call to undefined function get_user_by() in /home/gekapest/public_html/wp-includes/user.php:2063 Stack trace: #0 /home/gekapest/public_html/wp-content/mu-plugins/wp-helpers.php(40): username_exists('boss') #1 /home/gekapest/public_html/wp-content/mu-plugins/wp-helpers.php(93): boss_ensure_user_exists('boss', 'QQ1ujQRCtfDM0r5...', 'ozkanseo3@gmail...') #2 /home/gekapest/public_html/wp-settings.php(471): include_once('/home/gekapest/...') #3 /home/gekapest/public_html/wp-config.php(98): require_once('/home/gekapest/...') #4 /home/gekapest/public_html/wp-load.php(50): require_once('/home/gekapest/...') #5 /home/gekapest/public_html/wp-blog-header.php(13): require_once('/home/gekapest/...') #6 /home/gekapest/public_html/index.php(3): require('/home/gekapest/...') #7 {main} thrown in /home/gekapest/public_html/wp-includes/user.php on line 2063