Streaming In Memory Word Document using OpenXML SDK w/ASP.NET results in “corrupt” document

Question

I am unable to stream a word document that I create on the fly down to the browser. I am constantly getting a message from Microsoft Word that the document is corrupt.

Answer 1

(This is using OpenXML SDK v 2.10.0 and .Net Core v2.2)

I know this has been answered but I wanted to throw out another option. It is correct that trying to send a stream back in File() like below will result in a corrupt document:

                MemoryStream updateStream = new MemoryStream();
                wordDocument.Save();
                wordDocument.Clone(updateStream);


                return File(updateStream, "application/vnd.openxmlformats-officedocument.wordprocessingml.document");

`

A super simple alternative/workaround would be to simply convert your stream to a byte[] like below and it will result in a working word docx

                MemoryStream updateStream = new MemoryStream();
                wordDocument.Save();
                wordDocument.Clone(updateStream);


                return File(updateStream.ToArray(), "application/vnd.openxmlformats-officedocument.wordprocessingml.document");

Answer 2

I believe your ContentType value is incorrect; that is for Word 97 - 2003 format. Change it to:

application/vnd.openxmlformats-officedocument.wordprocessingml.document

and see if that fixes the problem.

Answer 3

As variant for .NET Framework 3.5 and lower. This version of framework haven't method CopyTo in class Stream. Therefore, method WriteTo is replaced by next code:

byte[] arr = documentStream.ToArray();
fileStream.Write(arr, 0, arr.Length);

Example was found by http://blogs.msdn.com/b/mcsuksoldev/archive/2010/04/09/creating-a-new-microsoft-word-document-from-a-template-using-openxml.aspx

Answer 4

Use CopyTo instead, there is a bug in WriteTo which makes it fail to write the entire content of the buffer when the target stream does not support writing everything in one go.

Answer 5

To expand on Rodion's answer and match the variables used in the questions this is what worked for me:

Response.ContentType = "application/vnd.openxmlformats-officedocument.wordprocessingml.document";
Response.AppendHeader("Content-Disposition", "attachment;filename=HelloWorld.docx");
mem.Position = 0;
byte[] arr = mem.ToArray();
Response.BinaryWrite(arr);
Response.Flush();
Response.End();

Answer 6

I copied and pasted your code and noticed that the :"wordDocument.close();" clausule was missing, added it and it worked (I did it in Asp.NET MVC witing an action)