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WU_E_UH_APPX_INVALID_PACKAGE_VOLUME
AppX packages are applications installed on Windows, but the AppX (or MSIX) format is unique. It’s been designed as a container instead of the traditional MSI or EXE installers you might be used to. AppX has advantages, too, like being able to make your app available in the Microsoft Store, and having additional security, since the apps run as per user, instead of as per machine.
And this, cool as it is, appears to be where we run into problems.
Microsoft appears to enumerate all the AppX packages upon a new-user logon. Then, in an effort to facilitate a good user experience, each AppX package is evaluated for things like DefaultAssociations (e.g., http == MSEdge) and FileTypeAssociations (e.g., “.pdf” == MSEdge). To make this process faster, it seems Microsoft tries to operate this asynchronously. This is both good and bad. It’s good, because the whole phase operates super quickly. It’s bad because CPU contention from multiple threads can slow the whole process down.
The challenge with all this enumerating, associating, and configuring is that it is time-consuming. The more AppX packages you have, the longer it takes. Windows Registry operations are slow to begin with, and get slower the larger your hive.
I highlighted this problem here, and the impact is more severe when you account for Speculative Execution patches. Add to that, the more AppX packages you have, the longer it takes to read/modify the hive, and so on. And this process happens TWICE. Once during the “User Profile” phase, and then again during the “Preparing Windows” phase.
There is a definite lack of documentation on this whole process, so almost everything appears to be via user discovery (like this document).
The stress of work amid the COVID-19 pandemic is quite enough on its own, but these AppX difficulties aren’t making things any easier for people. I can hear the frustration in the voices of our customers—and honestly in my own—when I don’t have an answer for their logons being slow because of AppX Packages. These people are onboarding thousands of users a week and this logon performance is, to say the least, not helping.