ASP.NET generate file to download Connection Reset

I'm trying to create a csv file bases on the contents of a gridview when a user clicks a button. However I keep getting Connection was reset by server when clicking the button. Thanks in advance.

    Protected Sub btnExport_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnExport.Click
    Try
        Dim out As IO.TextWriter = Response.Output
        Response.Clear()
        Response.ClearContent()
        Response.ClearHeaders()
        Response.Buffer = True
        Response.AddHeader("content-disposition", "attachment;filename=SearchResults.csv")
        Response.Charset = ""

        Response.ContentType = "application/text"

        gvFiles.AllowPaging = False
        gvFiles.DataBind()
        Me.EnableViewState = False
        'Bind DataTable to GridView

        'Search() method returns a DataTable of search results

        'gvFiles.DataSource = Search()
        'gvFiles.DataBind()

        'String builder class to add row data
        Dim sb As New StringBuilder()

        For k As Integer = 0 To gvFiles.Columns.Count - 1

            'add separator

            sb.Append(gvFil开发者_运维技巧es.Columns(k).HeaderText & ",")

        Next
        'append(New line)

        sb.Append(vbCrLf)
        'Get Rows
        For i As Integer = 0 To gvFiles.Rows.Count - 1
            'Get columns
            For k As Integer = 0 To gvFiles.Columns.Count - 1
                'add separator
                sb.Append(gvFiles.Rows(i).Cells(k).Text & ",")

            Next
            'append new line
            sb.Append(vbCrLf)
        Next

        out.Write(sb.ToString())

        out.Flush()

        'out.Close()
        Response.End()
    Catch ex As Exception
        Response.Write("Unable to generate File" & ex.ToString())
    End Try
End Sub

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I found the answer, I had to edit the web.config connection timeouts etc. because as it turns out it was generating such a large .csv file that the connection was timing out.