ajax get request导致内部服务器错误500

Question

我有一个PHP脚本返回前端，本地工作正常，当我上传到服务器它不再工作。有没有人知道修复或发现问题？不，它与数据库无关。

我还尝试了另一台服务器，所以我不认为它与服务器有关。

ajax get request

 $(document).ready(function () {
    var carid;
    var tabid;
    $(".button-collapse").sideNav()
    $('.modal').modal();
    $.ajax({
        method: 'get',
        url: 'api.php',
        dataType: 'html',
        contentType: 'application/json',
        data: {
            action: 'getmedisch'
        }
    }).done(function (data) {

接收php脚本：

switch ($_SERVER['REQUEST_METHOD']) {
  case'GET':
    $action = $_GET['action'];
    switch ($action) {
        case 'getmedisch':
            $content = new Content();
            $data = $content->get_content('medisch');
            $value = ' <div  class="col s3">
    <div id="newcard" object_id="NEW" class="card new">
        <div class="card-image">
            <img src="asset/bold.svg" style="width: 100%;  height: auto;">
            <div class="card-action zero-padding">
            </div>
        <div class="card-content">
            <h5>New Card</h5>
             </div>
    </div>
</div></div>';
            foreach ($data as $insert) {
                if($insert["online"]){$online= 'green online" ><i class="material-icons">visibility</i>';
                }else{$online= 'blue offline" ><i class="material-icons">visibility_off</i>';}
                $value .= '
        <div  class="col s3">
    <div id="cardobject" object_id="' . $insert["ID"] . '" class="card">
        <div class="card-image">
            <img  src="../asset/' . $insert["Foto"] . '" style="width: 100%;  height: auto;">
            <div class="card-action zero-padding">
                <div class="fixed-action-btn horizontal btn-card-midle" >
                    <a class="btn-floating btn-large red">
                        <i class="large material-icons">build</i>
                    </a>
                    <ul>
                        <li><a class=" delete btn-floating red"><i class="material-icons">delete</i></a></li>
                        <li><a class=" build btn-floating yellow darken-1"><i class="material-icons">mode_edit</i></a></li>
                        <li><a class=" status btn-floating ' . $online .'</a></li>

                    </ul>
                </div>
            </div>
        <div class="card-content">
            <h5>' . $insert["Titel"] . '</h5>

             </div>
    </div>
</div></div>
';
            }

echo $value;
            break;