Warning: require_once(//wp-includes/class-wpdb.php): Failed to open stream: No such file or directory in /wp-includes/load.php on line 668

Fatal error: Uncaught Error: Failed opening required '//wp-includes/class-wpdb.php' (include_path='.:/usr/local/share/pear') in /wp-includes/load.php:668 Stack trace: #0 /wp-settings.php(124): require_wp_db() #1 /wp-config.php(92): require_once('/wp-settings.ph...') #2 /wp-load.php(50): require_once('/wp-config.php') #3 /wp-blog-header.php(13): require_once('/wp-load.php') #4 /index.php(17): require('/wp-blog-header...') #5 {main} thrown in /wp-includes/load.php on line 668