title: How to solve "Error! The requested URL returned 500 - Internal Server Error"
body: <p>I'm working with Telerik Grid using databinding Ajax and MVC 3. The first problem I have is When I am going to Load data in Grid , the data loaded successfully. but Some times Its showing the pop up with error meassage "<strong>Error! The requested URL returned 500 - Internal Server Error</strong>". The second is when I try to filter a value in grid , I am getting the same exception But not in all times. </p>
  
  <p>Can anyone tell me, Why this Error is occuring Some of the times? And How can I solve this problem And How can I stop the error popup showing? Please giude me on this. Thanks.</p>
  
  <p>This is My View code:</p>
  
  <pre><code>@(
  Html.Telerik().Grid&lt;ItemValueView&gt;()
             .Name("ItemGrid")
             .Scrollable(scrollable =&gt; scrollable.Height("550px"))
             .ClientEvents(events =&gt; events
                                         .OnLoad("onLoad")                                                                                      .OnDataBound("onDataBound")
                                         .OnEdit("onEdit")
                                         //.OnSave("onSave")
             )
             .Editable(editing =&gt; editing.Mode(GridEditMode.InLine))
             .DataKeys(dataKeys =&gt; dataKeys.Add(i =&gt; i.ItemKey))
             .DataBinding(dataBinding =&gt; dataBinding
                                             //Ajax binding
                                             .Ajax()
                                             .OperationMode(GridOperationMode.Server)
                                             .Select("AjaxToolSelect", "SalesTool")
  
                                                                                           .Update("AjaxToolUpdate", "SalesTool")
             )
  
             .Columns(columns =&gt;
                          {
                              columns.Bound(i =&gt; i.CustomerName).Title("Customer").ReadOnly();
                              columns.Bound(i =&gt; i.DisplayClassKey).Title("Sub Class").ReadOnly();
                              columns.Bound(i =&gt; i.Place).Visible(false);
  }) 
                                      .Pageable(pager =&gt; pager.PageSize(50))
                                      .Sortable(sorting =&gt; sorting
                                      .SortMode(GridSortMode.MultipleColumn)
                                      .OrderBy(sortOrder =&gt;
                                                   {
                                                       sortOrder.Add(i =&gt; i.CustomerName);
                                                       sortOrder.Add(i =&gt; i.DisplayClassKey);
  
                                                   }))
             .Groupable(grouping =&gt; grouping
                                        .Groups(groups =&gt; groups.Add(g =&gt; g.CustomerName))
             )
             .Filterable()
  </code></pre>
  
  <p><strong>My Controller is:</strong></p>
  
  <pre><code>    [HttpPost]
      [GridAction]
      public ActionResult AjaxToolSelect()
      {
          var items = DataProvider.GetAllItems(true);
          var grid = new GridModel(items);
          return View(grid);
      }
  </code></pre>