Reactive Extensions in Windows Phone 8 and the 2001 submission error

3 minute read

You can read the whole story if you like reading, but this whole blog post comes down to one piece of advice:

If you value your sanity, do not, under any circumstances, pull in Reactive Extensions from NuGet into a Windows Phone 8 application. Use the built-in Microsoft.Phone.Reactive.dll instead. 

Those who follow me on twitter may have seen a few tweets pass by over problems I had with the Windows Phone 8 version of my app Map Mania. The submission went OK the first time, but the test team found two bugs – bugs that were also there in previous versions, but apparently they have ramped up the quality bar again. I can only applaud that, even if I got bitten by it myself, because the test report was comprehensive and showed someone actually understood or had read into some issues that may arise when using WMS services – and by doing so, succeeded in crashing my app.

Anyway, I fixed the app, resubmitted, and then the trouble started. Although the Store Test kit showed no errors, and submission went fine showing only validated XAP’s – after a few minutes I got an e-mail from the Windows Phone dev center:

Windows Phone Dev Center app submission

We weren't able to process the app submission for Map Mania.

Unfortunately, something happened with your Windows Phone app submission. Check the status of the submission in your app list at If the problem persists, contact support for assistance.

When I looked at the submission it said I had a “2001 error” with a helpful link, that leads you to a table in which it says:

There are duplicate files in AppManifest.xaml. Remove one of the files and then try again.

If rebuilding your XAP doesn't solve this problem, you may have to manually remove any duplicate files from the AppManifest.xaml in your XAP file. To rebuild your app, see Rebuilding your project in Visual Studio.

My friends, I have rebuilt the app till my fingers bled, cleaned the solution, then removed all the binaries manually, to no avail. Then I opened up the XAP to look for duplicate assemblies – there weren’t any duplicates; I scanned the AppManifest.xaml till I saw cross-eyed and didn’t find any duplicate entries there either - and after the 10th or so submit followed by automatic mail error within five minutes I gave up and indeed contacted Support.

I won’t go into full detail, but I think it’s fair to say this problem wasn’t easy to solve and Support struggled as much with it as I did. Quite some mails went back and forth, and the 9 hour time zone difference didn’t exactly work favorably for a quick resolve. It wasn’t until our Dutch DPE Matthijs Hoekstra, who I think now owe not only my sanity but possibly also my soul ;-), queried his sources and got back that a post-processing error apparently was being caused by System.Reactive.Core.dll and I was recommended to use Microsoft.Phone.Reactive.dll instead if possible.

I finally had a possible smoking gun - my own port of the #wp7nl library pulls in Reactive extensions from Nuget. So I removed the dependency from the library package, made a new local build, installed that into the app, compiled, uploaded and submitted, waiting for the inevitable dreaded 2001 error mail to pop up. Over an hour later, the only mail I got was from reminding me of a birthday and the app status at the moment of this writing says “Status: In signing stage". Hallelujah!

Now I don’t understand why submission went OK the first time and not the second time around. But I am very glad the issue is resolved. If you use my library, please remove the references it makes to the external reactive stuff manually or wait for me to publish the version that will do without. It will be out soon, I can tell you that.

Update: #wp7nl was updated within a few hours of this post. If you use the Windows Phone 8 version, please update to 3.0.1. Should you experience problems with missing assemblies, make a manual reference to Microsoft.Phone.Reactive.dll to the projects that use wp7nl. And please remove any reference to Rx* should they linger along.