winget upgrade should handle NSIS 'directory not empty' failures (exit code 2) more gracefully

[wukenadela]

Brief description of your issue

When winget upgrade runs an NSIS-based installer that refuses to install into a non-empty directory (exit code 2), winget reports the installation as failed with no recovery path. This is a common pattern with conda distributions (Miniforge3, Miniconda, Anaconda) whose NSIS installers reject non-empty target directories.

Related: microsoft/winget-pkgs#431894, conda-forge/miniforge#900

Steps to reproduce

1. Install Miniforge3 via winget: winget install CondaForge.Miniforge3
2. Attempt to upgrade: winget upgrade CondaForge.Miniforge3
3. winget invokes: Miniforge3-26.7.2-0-Windows-x86_64.exe /S /AllUsers /AddToPath=0 /RegisterPython=0
4. The installer terminates with exit code 2

Current behavior

winget reports:

Installer failed with exit code: 0x8a150003 : Executing command failed

The user is left with no working upgrade path — they must manually uninstall, reinstall, and restore their environments.

Suggested improvement

When an NSIS installer fails with exit code 2 (which often means "directory not empty" or a similar user-correctable condition), winget could:

1. Detect the specific NSIS exit code (exit code 2 is commonly used for "directory not empty")
2. Automatically attempt an uninstall-then-reinstall — run the existing installation's uninstaller first, then retry the installer
3. Or at minimum, provide a more helpful error message suggesting the user try winget uninstall <package> followed by winget install <package>

This would be a general improvement benefiting all NSIS-based packages that exhibit this behavior, not just Miniforge3.

Additional context

The Miniforge3 case is particularly painful because:

• The envs directory contains user-created conda environments that users want to preserve
• A simple uninstall+reinstall deletes these environments (see conda-forge/miniforge#448)
• The miniforge maintainers have marked this as wontfix, so the fix needs to come from the winget side

Environment

• OS: Windows 11 Pro, build 26200
• winget: v1.29.290
• Package: CondaForge.Miniforge3
• Architecture: x64
• Scope: machine (all users)

Note: This issue was drafted with AI assistance.

[SpecterShell]

microsoft/winget-pkgs#431894 (comment)