C# Console App - Set Content Type to Stream

Question

I'm working with a Console App that merges a DocX file from a template.

I'm using TemplateEngine.Docx and it almost works fine.

When I save my document from a stream, the file is corrupted. I can open it and everything is okay, but I've got an alert when opening it.

I think it's because I don't set a content type, but I don't know how to do it with a stream/FileStream.

A sample of my code :

Stream outputFile = GetFileFromId(6);
using(var outputDocument = new TemplateProcessor(outputFile).SetRemoveContentControls(true))
{
    outputDocument.FillContent(valuesToFill);
    outputDocument.SaveChanges();
    outputDocument.Document.Save(outputFile);
    FromStreamToFile(outputFile, OutputFilename);
}

public static void FromStreamToFile(Stream stream, string OutputFilePath)
{
        using(var fileStream = File.Create(OutputFilePath))
        {
            stream.Seek(0, SeekOrigin.Begin);
            stream.CopyTo(fileStream);
        }
}

Thanks for your help !