Uncompress String with nodejs that was compressed using a C# snippet

I collect some large log infos using a C# tool. Therefore I searched for a way to compress that giant string and I found this snippet to do the trick:

public static string CompressString(string text)
{
    byte[] buffer = Encoding.UTF8.GetBytes(text);
    var memoryStream = new MemoryStream();
    using (var gZipStream = new GZipStream(memoryStream, CompressionMode.Compress, true))
    {
        gZipStream.Write(buffer, 0, buffer.Length);
    }

    memoryStream.Position = 0;

    var compressedData = new byte[memoryStream.Length];
    memoryStream.Read(compressedData, 0, compressedData.Length);

    var gZipBuffer = new byte[compressedData.Length + 4];
    Buffer.BlockCopy(compressedData, 0, gZipBuffer, 4, compressedData.Length);
    Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, gZipBuffer, 0, 4);
    return Convert.ToBase64String(gZipBuffer);
}

After my logging action the C# tool sends this compressed String to a node.js REST interface which writes it into a database.

Now (in my naive understanding of compression) I thought that I could simply use something like the follwoing code on nodejs side to uncompress it:

zlib.gunzip(Buffer.from(compressedLogMessage, 'base64'), function(err, uncompressedLogMessage) {
  if(err) {
    console.error(err);
  }
  else {
    console.log(uncompressedLogMessage.toString('utf-8'));
  }
});

But I get the error:

{ Error: incorrect header check at Zlib._handle.onerror (zlib.js:370:17) errno: -3, code: 'Z_DATA_ERROR' }

It seems that the compression method does not match with the uncompression function. I expect that anyone with compression/uncompression knowledge could maybe see the issue(s) immediately.

What could I change or improve to make the uncompression work?

Thanks a lot!

via Fabian