ICSharpCode.SharpZipLib Compression method not supported PKZIP

Question

I have a problem with a zip-file created with the old PKZIP® Command Line for Windows version 4 from the year 2000. I am using ICSharpCode.SharpZipLib to extract the file. Windows has no problem to open the file in the Explorer. Here is the code:

private void Extract(string zipFile, string outputfolder)
{
  try
  {
    _logger.InfoFormat("Extracting {0}", zipFile);
    System.IO.Stream stream = new System.IO.FileStream(zipFile, System.IO.FileMode.Open);
    ZipInputStream zipInputStream = new ZipInputStream(stream);
    ZipEntry zipEntry = zipInputStream.GetNextEntry(); //Throws Compression error exception
    while (zipEntry != null)
    {
      String entryFileName = zipEntry.Name;
      _logger.InfoFormat("Entry-Filename: {0}", entryFileName);

      byte[] buffer = new byte[4096];
      String fullZipToPath = Path.Combine(outputfolder, entryFileName);
      string directoryName = Path.GetDirectoryName(fullZipToPath);
      if (directoryName.Length > 0)
      {
        Directory.CreateDirectory(directoryName);
      }

      using (FileStream streamWriter = File.Create(fullZipToPath))
      {
        StreamUtils.Copy(zipInputStream, streamWriter, buffer);
      }
      zipEntry = zipInputStream.GetNextEntry();
    }
  }
  catch (Exception ex)
  {
    _logger.Error("Error during extraction",ex);
    throw;
  }
}

Any idea how to fix this problem?

Answer 1

I had this same issue when decompressing a zip-file made with 7-zip.

I changed it from Deflate64 to Deflate, and then it worked.