Duplicate headers received from server

> Duplicate headers received from server > > The response from the server contained duplicate headers. This problem is generally the result of a misconfigured website or proxy. Only the website or proxy administrator can fix this issue. > > Error 349 (net::ERR_RESPONSE_HEADERS_MULTIPLE_CONTENT_DISPOSITION): Multiple distinct Content-Disposition headers received. This is disallowed to protect against HTTP response splitting attacks.

I found this error while exporting to pdf in chrome.

Response.Buffer = false;
Response.ClearHeaders();
string ext = objProp.PACKAGEFILENAME.Substring(objProp.PACKAGEFILENAME.LastIndexOf("."));
string ext1 = ext.Substring(1);
Response.ContentType = ext1;
Response.AddHeader("Content-Disposition", "target;_blank,attachment; filename=" + objProp.PACKAGEFILENAME);
const int ChunkSize = 1024;
byte[] binary = objProp.PACKAGEDOCUMENT;
System.IO.MemoryStream ms = new System.IO.MemoryStream(binary);
int SizeToWrite = ChunkSize;

for (int i = 0; i < binary.GetUpperBound(0) - 1; i = i + ChunkSize)
{
    if (!Response.IsClientConnected) return;
    if (i + ChunkSize >= binary.Length) SizeToWrite = binary.Length - i;
    byte[] chunk = new byte[SizeToWrite];
    ms.Read(chunk, 0, SizeToWrite);
    Response.BinaryWrite(chunk);
    Response.Flush();
}
Response.Close();

How to fix this?

This ones a little old but was high in the google ranking so I thought I would throw in the answer I found from https://stackoverflow.com/questions/8588818/chrome-pdf-display-duplicate-headers-received-from-the-server-fixed

Basically my problem also was that the filename contained commas. Do a replace on commas to remove them and you should be fine. My function to make a valid filename is below.

    public static string MakeValidFileName(string name)
    {
        string invalidChars = Regex.Escape(new string(System.IO.Path.GetInvalidFileNameChars()));
        string invalidReStr = string.Format(@"[{0}]+", invalidChars);
        string replace = Regex.Replace(name, invalidReStr, "_").Replace(";", "").Replace(",", "");
        return replace;
    }

The server SHOULD put double quotes around the filename, as mentioned by @cusman and @Touko in their replies.

For example:

Response.AddHeader("Content-Disposition", "attachment;filename=\"" + filename + "\"");

Just put a pair of double quotes around your file name like this:

this.Response.AddHeader("Content-disposition", $"attachment; filename="{outputFileName}"");

For me the issue was about a comma not in the filename but as below: -

Response.ok(streamingOutput,MediaType.APPLICATION_OCTET_STREAM_TYPE).header("content-disposition", "attachment, filename=your_file_name").build();

I accidentally put a comma after attachment. Got it resolved by replacing comma with a semicolon.

Double quotes around the filename in the header is the standard per MDN web docs. Omitting the quotes creates multiple opportunities for problems arising from characters in the filename.