Deploy and test WinUI3 app from an untrusted mount point


I have a MAUI app that I would like to test on Windows (which uses WinUI3 under the hood). However it uses a library with a very long path file that I cannot deploy (reported Github issue). I cannot shorten the folder any longer because it’s inside a larger project structure.

I thought about using Junction to shorten it:

New-Item New-Item -ItemType Junction -Path "D:\MyLongProjectPath" -Target "D:\Temp\Proj"

The build was successful but when deploying, I encounter another problem:

DEP0700: Registration of the app failed. [0x80073CF0] error 0x800701C0: Opening file from location: AppxManifest.xml failed with error: The path cannot be traversed because it contains an untrusted mount point.

How do I make a junction "trusted", or allow registering it from an untrusted mount point?

Note: I only need to do this for testing, it’s not for production.


The problem you are facing is related to .

One solution is to have some system process create this junction point for you. Note that simply running an elevated application may be not enough; by a system process, I mean some kernel-mode code able to create a point under a system process. We have just recently added a similar workaround for this "problem" (a security measure in fact, but for our customers it is a problem) to the CBFS Connect product.

What you may try to do for testing is redirect a request going to D:\Temp\Proj* to D:\MyLongProjectPath dynamically using CBFS Filter (a trial version will suffice). For this, you can add a reparse rule which will redirect requests. CBFS Filter doesn’t use reparse points on the disk and just returns STATUS_REPARSE to a file open request. I presume that this should be enough to prevent the OS from blocking the request due to the above-referenced mitigation.

IIRC, there are no samples for such reparsing, but the operation is trivial – a call to AddReparseRule and another call to start operations (you would need to install the driver that comes with CBFS Filter though, as it does all the heavy lifting).

Answered By – Eugene Mayevski 'Callback

This Answer collected from stackoverflow, is licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0

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