This is usually to do with either a Plugin or a Theme functions.php file.
It's usually an incorrect JSON string being sent or look for an add_action('save_post','SOME_FUNCTION'); call causing it.
This is usually to do with either a Plugin or a Theme functions.php file.
It's usually an incorrect JSON string being sent or look for an add_action('save_post','SOME_FUNCTION'); call causing it.