Fatal error: Class 'Walker' not found in /home/ihsan/public_html/wp-includes/class-walker-page.php on line 17

Fatal error: Uncaught Error: Class 'WP_Recovery_Mode_Email_Service' not found in /home/ihsan/public_html/wp-includes/class-wp-recovery-mode.php:84
Stack trace:
#0 /home/ihsan/public_html/wp-includes/error-protection.php(153): WP_Recovery_Mode->__construct()
#1 /home/ihsan/public_html/wp-includes/class-wp-fatal-error-handler.php(52): wp_recovery_mode()
#2 [internal function]: WP_Fatal_Error_Handler->handle()
#3 {main}
  thrown in /home/ihsan/public_html/wp-includes/class-wp-recovery-mode.php on line 84