public IActionResult GetById([FromRoute] string documentId) { var document = processor.GetDocument(documentId); if (document == null || document.Buffer == null) { return(NotFound()); } var fileContents = document.Buffer.ToMemoryStream(); var contentType = "application/vnd.openxmlformats-officedocument.wordprocessingml.document"; Response.Headers.Add("Access-Control-Expose-Headers", "Content-Disposition"); return(new FileContentResult(fileContents.ToArray(), contentType) { FileDownloadName = document.FileName }); }