Ajax错误:即使请求状态为200也调用函数

Here is my Ajax Call code:

以下是我的Ajax调用代码:

var name = $('#name').val();
var email = $('#email').val();
var password = $('#password').val();
$.ajax({
    type: 'POST',
    url: 'ajax.php',
    cache: false,
    data: { json : JSON.stringify({
        name:name,
        email:email,
        password:password
    })},
    dataType: 'json',

    success: function(){
        alert('request successful');
    },

    error: function(){
        alert('error occured');
    }

});
v