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As was announced, modern UI applications on Windows 10 will target new Universal Windows Platform which is kind of successor of Win RT. However in regards of development there is big difference as on previous version of Windows you have target the OS and now you are targeting specific versions of UWP. UWP will be updated at its own cadence and my ask here is, if there will be more versions of UWP available on the device and thus if there will be backwards app compatibility. Let me clarify my question on example. Lets say we have app which targets UWP of version 10069 what is also the max version tested. Will it be possible to run this app on device which has the UWP version e.g. 10166 installed?

Thank you.

marek_lani
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    Remember that all the version numbers to date are pre-RTM. You will need to snap to the first RTM version to get long-term support. – Chuck Walbourn Jul 13 '15 at 16:37

2 Answers2

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No, you will not be able to have your application run on a lower version of the UWP listed in your appxmanifest.

Update: Adding info from Chuck Walbourn, below.

To clarify, you can't run your application on a version of the platform that is older than the one you list as MinVersion. The MaxVersionTested indicates the version you actually tested against in case there's a need for appcompat shims in future versions of the UWP.

Dave Voyles
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  • To clarify, you can't run your application on a version of the platform that is older than the one you list as ``MinVersion``. The ``MaxVersionTested`` indicates the version you actually tested against in case there's a need for appcompat shims in future versions of the UWP. – Chuck Walbourn Jul 13 '15 at 16:42
  • Thanks for clarification. And just extending question, will there be more versions of UWP available on the one device/OS? I am targeting the scenario where I have apps which target lets say 10069 installed and my device will update to 101xx. Will suddenly the apps stop to work or will there be compatibility sustained? Thanks. – marek_lani Jul 13 '15 at 18:36
  • And just one more note, I was asking on the opposite scenario, if I can run the app which is targeting older version of UWP on a newer version of UWP. – marek_lani Jul 13 '15 at 18:38
  • Dave please let me note again: I was asking on the opposite scenario, if I can run the app which is targeting older version of UWP on a newer version of UWP – marek_lani Jul 23 '15 at 13:05
  • I see now. Yes, the UWP version you are targeting in the appxmanifest is simply stating what the *minimum* version required is. So if you are running a version of Windows which is great than, or equal to, the version of the UWP the app is targeting, you are OK. – Dave Voyles Jul 23 '15 at 17:34
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A UWP app targeting a lower version of UWP than the version of the targeted device will work. You will not be able to run an app that targets a high UWP version than the device you want to run on, so I think, from what you are asking, is good!

Also keep in mind that when declaring your MinSDK you want it to be as small as possible that makes sense. Your min should really only get higher as you target specific APIs that were not previously available or have changed and would break your code.

James Q Quick
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