Fatal error: Uncaught Error: Class 'WP_Customize_Setting' not found in /home/.sites/162/site1406375/web/LIVE/wp-includes/customize/class-wp-customize-nav-menu-setting.php:21
Stack trace:
#0 {main}
  thrown in /home/.sites/162/site1406375/web/LIVE/wp-includes/customize/class-wp-customize-nav-menu-setting.php on line 21