MSI: Registry entries not removed during uninstall

[lrandersson]

Describe the bug

When I run the uninstaller (MSI) the registry entries that were created during the installation are not removed. All of the registry entries in both locations:

1. Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\Folders
   One registry entry here for each installed file
2. Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall{GUID}
   still exist after uninstalling.

Unclear if there are any other registry entries created, but these are the ones I've seen.

Steps to reproduce

1. Build an installer according to the instructions here Initial MSI implementation, based on Briefcase conda/constructor#1084 (comment)
2. Run the installer with all the default options/settings (I only tried this so far when installed as "For me").
3. Verify the registry entries exist.
4. Uninstall the software again via the "Add or remove programs".
5. Confirm that the registry entries that they still exist.

Expected behavior

Registry entries created by the MSI installer are removed after uninstallation.

Screenshots

No response

Environment

• Operating System: Windows 11
• Python version: 3.13
• Software versions:
  • Briefcase: Listed in the link for reproducing the issue
  • Toga: None (I think?)
  • ...

Logs

No response

Additional context

No response

[freakboy3742]

Hrm... I can't reproduce this - the uninstall and file entries are all removed on my test MSIs. I am running on Win10... I doubt that would be causing the problem...

Are you able to share the actual MSI you built (so I can try and confirm if it's the MSI, or a Win10 issue)?

[lrandersson]

@freakboy3742 let me know if you received my message or not, I tried to send the installer to you a few days ago.

[freakboy3742]

@lrandersson I did; apologies for the delay responding.

So - I get a partial reproduction of what you've described. The Uninstall registry keys have been removed for me; and the only folder keys that have been retained are the ones for the Miniconda3 py313... folder, the conda-meta subfolder, the pkgs subfolder, and the subfolders for each of the packages in the pkgs folder - but not every subfolder of those folders - only the info folder.

I don't see this for any folders in my test project.

I can also see that there's a lot of extra content in that folder, so the uninstall has left a lot of content behind. I wonder if the problem might be that the folder can't be removed (because it's not empty), and as a result, the registry entry can't be removed?

[freakboy3742]

After some investigation, our current working theory is that this problem is caused by having leftover files in the install directory. The miniconda installer that is the test case here; it includes a post-install script that adds extra files to the install directory. It's the folders containing those files that are being retained as registry entries.

If we're correct, if an uninstall script is added that cleans up those extra files, the registry entries should also be cleaned up.

[lrandersson]

Hi @freakboy3742
Thanks for all the input. I've been able to verify now that the registry entries are removed if I clean-up the installation directory myself, feel free to close this issue.

To provide some background, in case anyone else reports the same issue in the future:
From my installation, I had a directory %FOO%\bar, and my registry entries were on the format

1. %FOO%\bar\a
2. %FOO%\bar\a\info
3. %FOO%\bar\b
4. %FOO%\bar\a\info
5. ...
   However from my post_install_script, files were added to these folders. Then, to "fix" the issue, during uninstall via pre_uninstall_script, I had to make sure every single file was removed such that the contents of %FOO%\bar basically matched what was written to my registry entry. When I did this, the registry entries were removed during the uninstall step.
   I had to write pre_uninstall_script to "remove everything inside %FOO%\bar except for the directories containing a directory called info, and if you encounter this directory info, remove the contents of info but not info itself", which seems very brittle.

[freakboy3742]

I'm going to keep this open as a documentation task - it's a fairly big "gotcha", especially if you're using post-install/pre-uninstall scripts. A comment in the "platform quirks" section of the MSI docs would make sense to me.