[No workaround] Shell Integration doesn't work for other users, and Unregister shell extension does nothing (cannot Register)

[scscgit]

When I switch to a different user on Windows 10, there is no shell integration to run WinMerge by right-clicking a file. It originally worked on my first user.

Thinking the installation only installed it for the first user, I uninstalled old version, and then installed the latest WinMerge-2.16.42.1-x64-Setup.exe variant for all users.

When I tried it on the second user, there was still no shell integration. So I went to settings and tried both buttons (Unregister shell extension and Register shell extension for current user only). They do absolutely nothing. And I realized that it doesn't work on my first user anymore either.

[sdottaka]

I was unable to reproduce this issue.
Does the second user have the "Add to context menu" checkbox checked?

[scscgit]

Yes, the options look the same on both users.

Are there any logs for the shell integration, or any debugging steps I could try?

[sdottaka]

Unfortunately there is no option to output logs.

Another thing to check is whether the second user has administrator privileges.

(This shouldn't be necessary if it's a per-user shell extension)

[Flyingscool]

I didn't realize how similar our bug reports are. I fixed the problem by copying the ShellExtensionX64.dll to ShellExtensionU.dll.

As I noted in my bug report, two windows pop up when clicking the "Register Shell Extension" buttons (I'm on Windows 11 Home on the machine I was having the context menu problem with). In the first window, when I displayed the details, it mentioned the ShellExtensionX64.dll, and in the second window it mentioned the ShellExtensionU.dll file. ShellExtensionU.dll did not exist in the directory, so I copied ShellExtensionX64.dll to ShellExtensionU.dll unregistered the options, then clicked the two Register buttons, and it added the context menu option.

[scscgit]

Yes, both users are admins. I also tried to run WinMerge as admin, and I still cannot register the shell extensions in either of them, because there is only the Unregister button. And I already have the ShellExtensionU.dll file there. Even if I copy it to ShellExtensionX64.dll, the Unregister button still doesn't cause the Register button to become available.