Is there a fix for the 'App Didn't Start' error in Visual Studio

This error appears when you try to deploy the project to the Local Machine (x64). There are no errors during build or deploy stages. However, when you try to run the machine you come up with this message after the App shows up momentarily and disappears immediately.

Trying to deploy to an emulator such as Mobile Emulator 10.0.14393.0 WVGA 4 Inch 512MB comes with the following errors. The emulator is running:

Severity Code Description Project File Line Suppression State
Error  DEP0001: Unexpected Error: SmartDeviceException - The system cannot find the file specified. [0x80131500] RMD   

However when you deploy it to a device (in this case Lumia 925) the app gets deployed with no errors.

In order to proceed to package it for uploading to the Windows Store I am not sure just deploying it to the device is good enough.

Is there a fix?

Yes. This was my fix.

https://hodentekhelp.blogspot.com/2018/09/what-is-right-target-version-that-works.html

How did you fix the Unhandled Exception 'the app didn't start' 0x8027025B ?

After having struggled over a week and half (http://hodentekhelp.blogspot.com/2018/08/is-visual-studio-community-2017-version.html), I decided to document what I do, a little more assiduously. It really did pay off!

The version of Microsoft Visual Studio Community 2017 is the latest 15.8.1 and now I believe the procedure would work in the earlier versions as well (I am not going to verify this, though). I am working with a Dell laptop using Windows 10 Pro Build 177733.rs5_release.180803-1525.

In one of my irate moments I might have attributed the problem to this build of Windows which I sincerely retract.

I created a Visual Studio UWP Blank Project and before I create a project, I need to choose the target version from this displayed screen.

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I accepted this default and created a project as shown. The MaiPage.xaml is displayed together with the Solution Explorer as shown. You now see that this error is in the designer.

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I believe that whether or not you can display in the designer is immaterial as far as Build is concerned, as it builds fine.

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'Deploy Solution' from the Build menu also works as seen here.

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You can run it in the Local Machine as shown here.

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Now I deploy to the device connected to the USB Port (Lumia 925).

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It works fine in the device.

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The only thing that is not working in this project is the 'DESIGNER'.

Now bring up the Project properties page as shown and choose a different version from the drop-down.

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I chose the Target version Windows 10 Fall Creators Update(10.0; Build 16290) and the Project got reloaded with the chosen Target version.

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The 'app didn't start' error did not go away and the designer is still unusable.

I went back to choose a different Target and Min versions as shown here:

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Voila! We have a hit.

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Now I must go back and verify the many earlier projects are still working.

August 22, 2018
Next, I tried to open one of the many UWP Projects that had worked earlier to the VS Community 2017 upgrades which had this error.

Well, they compiled well worked without any error. The designer had no problems.