IIS7 Response.WriteBuffer not working

Question

We have an ASP.NET 1.1 application that uses Crystal Reports to spit out an excel spreadsheet. The codes works under IIS6 but when we try to migrate it to IIS7 it is spitting out html with no content instead of the Excel file.

The MIME Type exists. Below is the code we are using. I did not write this code as I'm working primarily in 3.5 framework now. My assumption is I am missing something in the IIS7 configuration not the code since it works on IIS6. The rest of the ASP.NET 1.1 application works on IIS7.

        Dim cr As ReportClass
        'EXPORT the report based on the export type passed in.
        Dim ExpOptions As New ExportOptions
        Dim ContentType As String
        Dim strExt As String
        Trace.Write("DisplayReport reportname=" + ReportName + " SQL=" + SQL + " SQLSub1=" + Convert.ToString(Session("SQLSub1")))
        'Get the report filled with the data.
        If Session("SQLSub1") <> "" Then
            If Not Session("SubRptName") Is Nothing Then
                cr = PopulateReport(GetReportObject(ReportName), SQL, Session("SQLSub1"), Session("SubRptName"))
                Session("SQLSub1") = ""
                Session("SubRptName") = Nothing
            Else
                cr = PopulateReport(GetReportObject(ReportName), SQL, Session("SQLSub1"))
                Session("SQLSub1") = ""
            End If
        Else
            cr = PopulateReport(GetReportObject(ReportName), SQL)
        End If

        If DisplayType = ReportType.Excel Then
            If ReportName.ToUpper = "ACTION" Or ReportName.ToUpper = "INVENTORY_EXCEL" _
                Or ReportName.ToUpper = "UNDERPERFORM" Or ReportName.ToUpper = "EMPLOYEE_EXCEL" Then
                Dim excelFormatOpts As New ExcelFormatOptions
                ' Set the excel format options.
                excelFormatOpts.ExcelTabHasColumnHeadings = True
                excelFormatOpts.ExcelUseConstantColumnWidth = False
                ExpOptions.FormatOptions = excelFormatOpts
            Else
                ExpOptions.FormatOptions = New ExcelFormatOptions
            End If
            ExpOptions.ExportFormatType = ExportFormatType.Excel
            ContentType = "application/vnd.ms-excel"
            strExt = ".xls"
        ElseIf DisplayType = ReportType.PDF Then
            ExpOptions.ExportFormatType = ExportFormatType.PortableDocFormat
            ExpOptions.FormatOptions = New PdfRtfWordFormatOptions
            ContentType = "application/pdf"
            strExt = ".pdf"
        End If

        'Stream the report to the screen
        Dim req As New ExportRequestContext
        req.ExportInfo = ExpOptions

        Dim s As Stream
        Try
            s = cr.FormatEngine.ExportToStream(req)
        Catch ex As Exception
            Trace.Warn("DisplayReport cr.FormatEngine.ExportToStream(req) failed: " + ex.Message)
            Dim x As String = String.Empty
        End Try


        Response.Clear()
        'Response.ClearHeaders()
        'Response.ClearContent()
        Response.Buffer = True
        Response.ContentType = ContentType
        Response.AddHeader("Content-Type", ContentType)


        Dim buffer(s.Length) As Byte
        s.Read(buffer, 0, Int(s.Length))
        Response.BinaryWrite(buffer)

        Dim strContentDisposition As String = "inline;filename=" & ReportName.ToString.ToLower & strExt.ToString
        Trace.Write("DisplayReport strContentDisposition=" + strContentDisposition)
        Response.AddHeader("Content-Disposition", strContentDisposition)
        Response.Cache.SetMaxAge(New TimeSpan(0, 0, 10))
        Response.End()

Answer 1

Asked some devs here at work, this is what I got so far:

"Never seen that before, I’ve never even used the export to stream option in crystal before. However, if I were to guess, I would look at server permissions as a possible fault. I’ve seen situations where the user has to have special privileges to access streams."