Error when using Gridview in user control and send as a string to jquery ajax

I have a user control with a gridview and call from a web method. This works fine from local machine and show the data in gridview but when I publish the website on the server gridview doesn’t show and ajax error shows :Internal server error.

user control:

<div>  <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="true"> </asp:GridView></div>

[WebMethod(EnableSession=true)]
publicstaticstringGetSelectedFolder(intFolderID)
{
 Page page =newPage();
 UCFilesUCFiles=(UCFiles)page.LoadControl("uc/UCFiles.ascx");
UCFiles.ID ="ucUpload"; page.Controls.Add(UCFiles);HtmlForm tempForm =newHtmlForm();
 tempForm.Controls.Add(UCFiles);
 page.Controls.Add(tempForm);StringWriter output =newStringWriter();
 HttpContext.Current.Server.Execute(page, output,false);
 string outputToReturn = output.ToString();
 // HttpContext.Current.Server.HtmlEncode(outputToReturn, output);
 //outputToReturn = outputToReturn.Substring(outputToReturn.IndexOf("<div>"));
//outputToReturn = outputToReturn.Substring(0, outputToReturn.IndexOf("</form>"));
return outputToReturn;

$.ajax({
 type:"POST",
 url:"File.aspx/GetSelectedFolder",
 contentType:"application/json; charset=utf-8",
 data:"{'FolderID': '"+ jQuery.attr(data.rslt.obj[0],"id")+"'}",
 dataType:"json",
 success:function(response)
 {
 alert(response.d);
  $("#div2").html(response.d);
  },
 error:function(XMLHttpRequest, textStatus, errorThrown)
 {
 alert("Status: "+ textStatus); alert("Error: "+ errorThrown);
 }
});