File downloads failing on Android

Question

I need to allow users to download files from our server, and I'd like to serve these files via an ASP.NET MVC 5 controller action. My action looks like this:

public FileContentResult Download(int fileId)
{
    var myContent = GetContentForFile(fileId);
    var myFileMeta = GetFileMeta(fileId);

    if (myContent == null || myFileMeta == null)
        throw new FriendlyException("The file or its associated data could not be found.");

    return File(myContent.Content, myContent.MediaType, myFileMeta.FileName);
}

The above is as simple as I could get it, it works fine on PC and iPhone, but not on Android. Using Fiddler, I can see that the following response headers when I try to download one of my files - in this case a JPG file called "1447114384146-643143584.jpg":

HTTP/1.1 200 OK
Cache-Control: private, s-maxage=0
Content-Type: image/jpeg
Server: Microsoft-IIS/8.5
X-AspNetMvc-Version: 5.2
Content-Disposition: attachment; filename=1447114384146-643143584.jpg
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
Date: Thu, 12 Nov 2015 23:09:00 GMT
Content-Length: 1682868

Note that I don't have any reliable way to know the correct MIME-type - is this an issue and could it explain why the file isn't being downloaded in Android?

To clarify, when I attempt to download any file from the database using Android, I get a toast notification telling me "Download started", but then the download sits in the queue for a while on 0% before eventually just changing to "Failed".

What I've tried

I've tried all manner of things that people have suggested in similar questions, most of which are to do with the content-disposition header or the content-type header. I've tried forcing the content-type header to application/octet-stream for every file, I've tried sending the correct content-type header for the particular file. I've tried manually sending the content-disposition header. I've tried forcing the filename extension to uppercase.

None of the above has worked, in fact none of them have had any impact at all on the problem, for better OR worse. I'm amazed that this is so hard - I feel like I must be missing something obvious?

Additional information

Browser: latest Chrome on Android
OS: Android 5.1 (also occurs for a coworker on their Android phone which is at an earlier Android version (not sure which specifically), so I don't think this is tied to a specific Android version).

Update

After reading this blog entry: http://www.digiblog.de/2011/04/android-and-the-download-file-headers/ I tried following the advice and set my headers exactly as suggested:

HTTP/1.1 200 OK
Cache-Control: private, s-maxage=0
Content-Type: application/octet-stream
Server: Microsoft-IIS/8.5
X-AspNetMvc-Version: 5.2
Content-Disposition: attachment; filename="1447114384146-643143584.JPG"
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
Date: Thu, 12 Nov 2015 23:42:18 GMT
Content-Length: 1682868

Again, this had no impact on the problem at all.

Futher update

I have been able to test on a Marshmallow (Android v6.0) device and the download works. It seems to be a pre-Marshmallow issue.

Nick Coad · Accepted Answer

Sadly this was caused by something very specific to my environment, but I'd like to put the answer here in case anyone else stumbles across this same problem.

It turns out the Android download manager doesn't like underscores in domain names, and our local domain address had an underscore in it. I used the server's IP address instead and everything worked as expected.

For example this: http://www.my_domain.com.au/file.png won't work. This: http://192.168.x.x/file.png does work.

Found as an answer on this question: Trouble downloading file from browser on Android

File downloads failing on Android

Answers (2)

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