Unzipping A Zip File-The Magic Number In GZip Header Is Not Correct.Make Sure You Are Passing In A GZip Stream.

I have the following code in an SSIS package and I get the following error:

Error: 0x0 at Unzip downloaded file, Boolean ReadGzipHeader(): Unable to decompress C:ETLPOSDataIngramWeeklyINVEN.zip; The magic number in GZip header is not correct. Make sure you are passing in a GZip stream.

Error: 0x4 at Unzip downloaded file: The Script returned a failure result.

Task failed: Unzip downloaded file

The zip file unzips perfectly using winzip utility, so that file is definitely not a problem here.

The code I am using in a script task is as follows:

' Microsoft SQL Server Integration Services Script Task

' Write scripts using Microsoft Visual Basic

' The ScriptMain class is the entry point of the Script Task.

Imports System

Imports System.Data

Imports System.Math

Imports Microsoft.SqlServer.Dts.Runtime

Imports System.IO

Imports System.Text

Imports System.IO.Compression

Public Class ScriptMain

' The execution engine calls this method when the task executes.

' To access the object model, use the Dts object. Connections, variables, events,

' and logging features are available as static members of the Dts class.

' Before returning from this method, set the value of Dts.TaskResult to indicate success or failure.

'

' To open Code and Text Editor Help, press F1.

' To open Object Browser, press Ctrl+Alt+J.

Public Sub Main()

'

' Add your code here

'

Dts.TaskResult = Dts.Results.Success

Dim success As Boolean = True

Dim workFilePath As String

workFilePath = Dts.Variables("zipFilePath").Value.ToString()

If File.Exists(workFilePath) Then

If Not workFilePath.EndsWith(".zip") Then

Dts.Events.FireInformation(0, "", workFilePath + " is not compressed; skipping decompression", Nothing, -1, True)

Return

End If

Dim uncompressedFileName As String

Dim bytes(Int16.MaxValue) As Byte

Dim n As Integer = 1

Try

uncompressedFileName = Dts.Variables("unCompressedFileName").Value.ToString()

Dts.Events.FireInformation(0, "", "decompressing " + workFilePath + " to " + uncompressedFileName, Nothing, -1, True)

Using writer As New FileStream(uncompressedFileName, FileMode.Create)

Using compressedStream As Stream = File.Open(workFilePath, FileMode.Open, FileAccess.Read, FileShare.None)

Using unzipper As New GZipStream(compressedStream, CompressionMode.Decompress)

Do Until n = 0

n = unzipper.Read(bytes, 0, bytes.Length)

writer.Write(bytes, 0, n)

Loop

unzipper.Close()

End Using

compressedStream.Close()

End Using

writer.Close()

End Using

Catch ex As Exception

Dts.Events.FireError(0, ex.TargetSite().ToString(), "Unable to decompress " + workFilePath + "; " + ex.Message, Nothing, -1)

success = False

Finally

If success = False And File.Exists(uncompressedFileName) Then

Dts.TaskResult = Dts.Results.Failure

File.Delete(uncompressedFileName)

End If

End Try

Else

Dts.Events.FireError(0, "", workFilePath + " does not exist", Nothing, -1)

Dts.TaskResult = Dts.Results.Failure

Return

End If

End Sub

End Class

Instead of the GZipStream do I have to use some other stream class for a zip file.  Please let me know.

Thanks,

Monisha