Fatal error: Uncaught Error: Call to undefined function wp_using_themes() in /home/ryuta28/www/ryutahatsuzawa/wp-includes/template-loader.php:7
Stack trace:
#0 /home/ryuta28/www/ryutahatsuzawa/wp-blog-header.php(19): require_once()
#1 /home/ryuta28/www/ryutahatsuzawa/index.php(17): require('/home/ryuta28/w...')
#2 {main}
thrown in /home/ryuta28/www/ryutahatsuzawa/wp-includes/template-loader.php on line 7