I have a developer unlocked Lumia 635 just yesterday updated to Windows 10 Mobile Technical Preview (OS version: 10.0.12562.84).
After creating "Blank App (Windows Universal)" targeting Windows Phone 10 in Visual Studio 2015 RC and tried to deploy it to the device (and have changed configuration to ARM for that exactly purpose) I've got this error:
Error : DEP0001 : Unexpected Error: A Prerequisite for an install could not be satisfied. (Exception from HRESULT: 0x80073CFD)
After quick look at the app "references" it is turns out there are some of them specific to Application Insights (and few others) with disregard to the fact that I've specifically unchecked the Application Insights integration on project creation dialog before (surprise!). So I've removed them all leaving only the following (seems like unremovable):
But this didn't help, unfortunately - still can't deploy this "default" app to the phone.
Though, deployment of my current working universal app that target Windows Phone 8.1, to this phone was just flawless.
Working OS is Windows 8.1 Pro, if that matter.
Update
Strike-through text above is not important anymore, see accepted answer.
I'm on the .NET/UWP team. The official answer from Microsoft is here:
https://msdn.microsoft.com/en-us/library/windows/apps/dn706236.aspx?f=255&MSPPError=-2147217396
Let me write out the steps from that link above. These steps apply today (May 20th 2015, using VS2015 RC that was released at BUILD.) Deploying to mobile was not possible prior to May14, when the correct build of Win10 Mobile came out.
Your machine should be running Windows 10, build 10074 or higher, from here: https://insider.windows.com/
Install VS2015 RC from here: https://www.visualstudio.com/en-us/downloads/visual-studio-2015-downloads-vs.aspx
You can run Win10 apps upon emulators. The emulators came with the Win10 SDK, and so are running version 10069 of the Win10.Mobile operating system.
You can run Win10 apps on your local machine. To do this you local machine must be Win10.Desktop version 10074 or higher and must be unlocked.
You can run Win10 apps on your phone. To do this your phone must be Win10.Mobile version 10080 or higher (which came out on May 14th). Your phone must be unlocked.
The key fact about Win10 is that you can write software against one particular SDK (e.g. the 10069 SDK that came out at //BUILD), and still run it on a more recent version of Win10 (e.g. 10074 that's current for Win10.Desktop program, or 10080 that's current for Win10.Mobile insider program).
In the .appxmanifest file, MinVersion="10.0.10069.0" says that your app will refuse to deploy to any machine which is running a lower version of Win10.
In the .appxmanifest file, MaxVersionTested="10.0.10074.0" says that if your app is deployed to a machine which is running a higher version of Win10, then it might have to do "quirking".
Both of these things are controlled by the Project>Properties dialog, and are actually stored in the .csproj/.vbproj.
The answers by @user4855870, @Rexobias and @Sevenate were hacks. They were sticking in an artificially low version for MinVersion to work around the fact they hadn't yet updated their devices. That's a fair approach (and I did it while I was waiting for Win10.Mobile 10080 build to be released). But now that it has been released, there's no need for these hacks, and you should just update your device.