Unknown Network Error when export file

Question

I would like to get all specific files in Document Library and export them as a zip file.

The bellow code block works well when I call it from Page Layouts, or Web Parts, but does not work when I call under a my custom Rest service. Say the zip file is 10mb, when a hit the link to download the file on browser, it downloads nearly 10mb and suddenly throws Unknown Network Error. I believe that there is something wrong with response and buffer here, for example the response ended before the buffer flushes all contents. Just my thought. Please advise.

        response.Clear();
        response.BufferOutput = false;

        System.Web.HttpContext c = System.Web.HttpContext.Current;
        string archiveName = String.Format("archive-{0}.zip", filename);
        response.ContentType = "application/zip";
        response.AddHeader("content-disposition", "inline; filename=\"" + archiveName + "\"");
        try
        {
            using (var ms = new System.IO.MemoryStream())
            {
                using (ZipFile zip = new ZipFile())
                {
                    foreach (SPListItem item in items)
                    {
                        if (item.ContentType.Name != "Folder")
                        {
                            var file = item.File;
                            var content = file.OpenBinary(SPOpenBinaryOptions.None);
                            zip.AddEntry(file.Name, content);
                        }
                    }
                    zip.Save(ms);
                }
                ms.Position = 0;
                var b = new byte[1024];
                int n;
                while ((n = ms.Read(b, 0, b.Length)) > 0)
                    response.OutputStream.Write(b, 0, n);

Answer 1

Can you try by adding a content-length to the Response?

response.AddHeader("Content-Length", ms.Length);

right before ms.Position = 0;