Q:

Error: This page can't be reached in Kartik Yii2 Export

In Kartik Yii2 Export, While exporting as Excel am getting This Page Cant't Reached Error in Localhost.
if i export as Text or CSV, export get worked but if i open the exported file Text or CSV, Half the 
report is printing like html code
Help will be really appreciated.
GridCode:
 <?php $gridColumns = [
            ['class' => 'yii\grid\SerialColumn'],
                'membercode',
                'member_name',
                [
                   'attribute' => 'payment_category',
                   'format' => 'raw',
                   'label' => 'Payment Category',
                   'value' => function($model, $key, $index, $grid) {
                        $temp = $model->payment_category;
                        $si = Category::find()->where(['category_id' => $temp])->one();
                        return $si['category_name'];
                    },  
                ],
                'member_gender',
                'member_address:ntext',
                'payment_date',
                'amount',
                'receipt_no',
                'payment_mode',
                'pledge_amount',
                'young_amount',
                'tv_amount',
                'building_amount',
                [
                   'attribute' => 'payment_subcategory',
                   'format' => 'raw',
                   'value' => function($model, $key, $index, $grid) {
                        $exp = explode(',', $model->payment_subcategory);
                        $relation_name = ArrayHelper::map(Subcategory::find()->where(['subcategory_id' => $exp])->all(), 'subcategory_id', 'subcategory_name');
                        $relation = implode(',', $relation_name);
                        return $relation;
                    },
                    'filter' => Html::activeDropDownList($searchModel, 'payment_subcategory', ArrayHelper::map(Subcategory::find()->asArray()->all(), 'id', 'subcategory_name'),['class'=>'form-control','multiple' => true]),
                ],
            ['class' => 'yii\grid\ActionColumn'],
        ]; ?>

    <?= ExportMenu::widget([
            'dataProvider' => $dataProvider,
            'columns' => $gridColumns,
            'columnSelectorOptions'=>[
                'label' => 'Columns',
                'class' => 'btn btn-danger'
            ],
            'fontAwesome' => true,
            'dropdownOptions' => [
                'label' => 'Export All',
                'class' => 'btn btn-primary'
            ]
        ]); ?>

    <?= GridView::widget([
        'dataProvider' => $dataProvider,
        'filterModel' => $searchModel,
        'columns' => $gridColumns,
        'pager' => [
            'firstPageLabel' => 'First',
            'lastPageLabel' => 'Last',
        ],
    ]); ?>

Above is my Grid view Code.
Help will be really appreciated.
Updated:
Error geeting while exporting as CSV:

Error geeting while exporting as EXCEL

A:

There is an issue in your gridview, one of the field in gridview carries "=" equal to sign. please check it out PhpOffice/PhpExcel

