I encountered a similar problem like HumanEclectic – with the plugin stops working customize.php =(
The reason for this work is that part of the script:
function ds_override_load_customizer_action () {
wp_die (__ ( ‘The Customizer is currently disabled.’));
}
When you try to install the plug-in Toggle Meta Boxes (v3.8.1.1) to change the Menus (v4.3) settings site stopped working by generating “500 Internal Server Error”