laravel csrf_token无法识别的问题

报错提示

前端代码

<div class="container">
    <form method="post" action="/data">
        {{ csrf_field() }}
        <input type="text" name="name">
        <input type="submit" value="提交">
    </form>
</div>

后端代码

Route::group(['middleware'=>'web'], function (){
    Route::get('/form', function(){
        return view('form');
    });
    Route::post('/data', function (){
        return dd($_POST);
    });
});

检查了session文件发现数据提交前后token值不一致
提交前

a:4:{s:6:"_token";s:40:"DOj01mDDBWNLJ11UWQ3LBgthXLPud5Lx4mCYF2pS";s:9:"_previous";a:1:{s:3:"url";s:28:"http://www.justonce.net/form";}s:9:"_sf2_meta";a:3:{s:1:"u";i:1481014874;s:1:"c";i:1481014874;s:1:"l";s:1:"0";}s:5:"flash";a:2:{s:3:"old";a:0:{}s:3:"new";a:0:{}}}

提交后

a:3:{s:6:"_token";s:40:"zQOa0WiEdD9UFjKhNdHwEHwfMkAbqk3Dp5khKPC0";s:9:"_sf2_meta";a:3:{s:1:"u";i:1481014892;s:1:"c";i:1481014892;s:1:"l";s:1:"0";}s:5:"flash";a:2:{s:3:"old";a:0:{}s:3:"new";a:0:{}}}