App-V Shell Extensions Broken in Windows 10 1903/1909 (Now Fixed!)

Shell extensions for App-V packages are broken in Windows 10 1903 and 1909. Previous OS versions are OK, even when fully patched.

This issue has now been fixed in the KB4550945 update, released 21st April 2020!

Here’s an example when trying to use the context menu from 7-Zip. The menu still appears but generates an error when trying to use it:

Note that you can also see this error on 1809 and previous if you enable App-V for the first time then try to use this functionality before rebooting.