Excel – Unable to evaluate expression because the code is optimized or a native frame is on top of the call stack

asp.netdownloadexcelgridview

I have download link present in grid view and when I click on it, a save dialogue pop up will appeared and an Excel fill will be downloaded.

But I am getting error "Unable to evaluate expression because the code is optimized or a native frame is on top of the call stack." on Response.End().

Code : 

protected void grdFiles_RowCommand(object sender, GridViewCommandEventArgs e)
    {

        try
        {
            if (e.CommandName == "download")
            {
                string _FileName = Convert.ToString(e.CommandArgument);
                //Response.Clear();
                //Response.AppendHeader("Content-Disposition", "attachment; filename=" + _FileName);
                //Response.ContentType = "application//octet-stream";
                //Response.TransmitFile(Server.MapPath("~/Files/" + _FileName));
                //Response.End();

                // Get the physical Path of the file(test.doc)
                string filepath = Server.MapPath("test.doc");

                // Create New instance of FileInfo class to get the properties of the file being downloaded
                FileInfo file = new FileInfo(Server.MapPath("~/Files/" + _FileName));

                // Checking if file exists
                if (file.Exists)
                {
                    // Clear the content of the response
                    Response.ClearContent();

                    // LINE1: Add the file name and attachment, which will force the open/cance/save dialog to show, to the header
                    Response.AddHeader("Content-Disposition", "attachment; filename=" + file.Name);

                    // Add the file size into the response header
                    Response.AddHeader("Content-Length", file.Length.ToString());

                    // Set the ContentType
                    Response.ContentType = "application/vnd.ms-excel";

                    // Write the file into the response (TransmitFile is for ASP.NET 2.0. In ASP.NET 1.1 you have to use WriteFile instead)
                    Response.TransmitFile(file.FullName);

                    // End the response
                    Response.End();
                }
            }
        }
        catch (Exception ex)
        {

        }
    }

Best Answer

Another possible cause of this error, could possibly be because your grid is in an update panel?

If this is the case I would recommend that you add your grid control as a Post back trigger as such:

<asp:UpdatePanel runat="server" ID="UpdatePanel1">
    <Triggers>
        <asp:PostBackTrigger ControlID="grdFiles" />
    </Triggers>
    <ContentTemplate>
        <gridview ID="grdFiles" runat="server">
        your grid view content
        </gridview>
    </ContentTemplate>
</asp:UpdatePanel>

Though putting an entire grid as a Post back trigger might be overkill (post backs on paging might occur etc.), you could try creating your download link as a template column and set the control inside the grid as the post back trigger.

I had a similar problem where I used an Export button as a download button instead, and use the grid command to select a detail and make this button available only when something in the grid is selected then place a post back trigger on this button instead of having it on the grid.

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