jquery.js：8630 POST http://127.0.0.1:8000/quiz/save-question-result/1 500（内部服务器错误）

Question

我有使用AJAX提交的表格，但是当我尝试提交时却失败了。 错误的console.log是：

POST http://127.0.0.1:8000/quiz/save-question-result/1 500 (Internal Server Error)
send @ jquery.js:8630
ajax @ jquery.js:8166
(anonymous) @ 1:374
dispatch @ jquery.js:4435
r.handle @ jquery.js:4121

我的表单和Ajax sumbit

  @foreach($questions as $question)
<div class="jumbotron" id="jumbotron{{$question->id}}"
    @if($question->id != $current_question_id)
    style="display: none;"
    @endif
    >
    <p>Question #{{$question->id}}</p>
    <p>{{$question->question}}</p>

    {!! Form::open(['action'=>['QuizDataController@postSaveQuestionResult', $categoryquiz->id], 'method'=>'post', 'id'=>'frm'.$question->id]) !!}

    <div id="answer-radio{{$question->id}}">
        <div class="btn-group" data-toggle="buttons">

            <li>
                <label>
                    <input type="radio" name="option" value="1" /> {{$question->option1}}
                </label>
            </li>
            <li>
                <label>
                    <input type="radio" name="option" value="2" /> {{$question->option2}}
                </label>
            </li>
            <li>
                <label>
                    <input type="radio" name="option" value="3" /> {{$question->option3}}
                </label>
            </li>
            <li>
                <label>
                    <input type="radio" name="option" value="4" /> {{$question->option4}}
                </label>
            </li>

        </div>
    </div>

    {!! Form::input('hidden','question_id', $question->id) !!}
    {!! Form::input('hidden','time_taken'.$question->id,null,['id'=>'time_taken'.$question->id]) !!}

    {!! Form::token() !!}



    @if($question->id == $last_question_id)
    {!! Form::submit('Last', ['class'=>'btn btn-info']) !!}
    @else
    {!! Form::submit('Next', ['class'=>'btn btn-info']) !!}
    @endif
    {!! Form::close() !!}
</div>

@if($questions->count()>1)
@section('script_form')
$.ajaxSetup({
            headers:{
                'X-CSRF-TOKEN':"{{ csrf_token() }}"
            }
        });
$(function() {

    //console.log({{$question->id}});
    //console.log({{$last_question_id}});
    {{-- $('#frm{!!$question->id!!}').off('submit'); --}}
    $('#frm{!!$question->id!!}').on('submit', function(e){

        e.preventDefault();


        $.ajax({
            url: $('#frm{!!$question->id!!}').attr('action'),
            data: $('#frm{!!$question->id!!}').serialize(),
            cache: false,
            contentType: false,
            processData: false,
            enctype: "multipart/form-data",
            type: 'POST',
            success: function(data){
                data = JSON.parse(data);

                if (data.success)
                alert('success!');
                else
                alert('got failure response from PHP');

            },
            error:function(xhr, status, error) {
                var err = eval("(" + xhr.responseText + ")");
                console.log(err.Message);
              }
        });

        {{-- $.post($formAction, $(this).serialize(), function(data){

            //if(data.next_question_id != null)
            $('#jumbotron{{$question->id}}').css('display','none');
            //console.log(data.next_question_id);

            $('#jumbotron' + data.next_question_id+'').css('display','block');
        }); --}}



    });
});