explorer.exe does not start after update

[jaanika-m]

Issue: The update causes explorer.exe to restart, and there are causes where explorer.exe does not start automatically afterward.
We have a bigger amount of machines where we perform a silent background update. Users definitely would not appreciate if their explorer stops working.

Current workaround: I have added a command to start explorer.exe, but during testing, some test users experienced a slight delay, which is also not desirable.

Additionally, I would like to mention that I don’t believe this is related to our specific setup, as I experienced the same issue on my personal machine.

[metsma]

The behavior is caused by the shell extension DLL that our installer registers with Windows Explorer. This DLL is loaded into explorer.exe whenever a user opens the context menu (right-click) on a file, because it provides the "Sign" / "Encrypt" options directly inside Explorer.

During an update, Windows Installer cannot unload a shell extension DLL that is currently in use. The only way for the system to release that DLL is to restart explorer.exe, which Windows Installer does automatically. On some systems, Explorer restarts immediately; on others, depending on timing or system load, Explorer may not restart as quickly, which results in a brief interruption for the user.

This is not specific to our environment — it is a general limitation of classic shell extensions and affects all software that integrates into the Explorer process.

A modern alternative is available:
We have introduced a new shell extension implemented for MSIX packages, which avoids this problem entirely, because the extension is packaged and isolated differently. The implementation is available here:
#1356