When you need to display some information via pop up window, it's better to use jquery-ui dialog than Telerik window. Not only because the Telerik is not supported any more, but also because the jquery-ui dialog can behaves much better, pure client side and with even less and simpler code!

Step-by-step guide

1. Reference jquery-ui script in your html:

   <script type="text/javascript" src="@Url.Content("~/Scripts/libs/jquery-ui.min.js")"></script>

2. Add a placeholder div like this, and delete the original Telerik placeholder:

   <!-- Add a pure html placeholder -->
   <div id="dispatching-history-report-window" title="Dispatching History" style="display: none;"></div>
   
   <!-- Delete the following Telerik placeholder -->
   @(Html.Telerik().Window().Modal(true)
   		   .Name("DispatchingHistoryReportWindow")
   		   .Title("Dispatching History")
   		   .Buttons(buttons => buttons.Maximize().Close())
   		   .Width(800).Resizable(resizing => resizing.Enabled(true))
   		   .Height(440)
   		   .Visible(false).Scrollable(false)
   	  .Draggable(true))

3. Update the popup code as below shows:

   // Original pop up using Telerik window
   $("#DispatchingHistoryReportWindow").data('tWindow').center().open().content("Loading...").ajaxRequest(url);
   
   // Updated pop up using jquery-ui dialog
   var $dialog = $("#dispatching-history-report-window");
   
   var dialogOptions = {
   	height: "auto",
   	width: "auto",
   	position: "center",
   	modal: true
   };
   
   $dialog
   	.dialog(dialogOptions)
   	.html("
   Loading...
   ");
   
   $.ajax({
   	url: url,
   	cache: true,
   	dataType: "html",
   	success: function (page) {
   		$dialog
   			.html(page)
   			.dialog(dialogOptions)
   	}
   });

4. Done!