winui-packaging

SkillCloud & infra

MSIX packaging, code signing, and distribution for WinUI 3 apps — build for release, certificate generation (winapp cert generate), certificate trust, code signing (winapp sign), self-contained deployment, CI/CD with GitHub Actions, and Microsoft Store submission. Use when preparing for release, creating MSIX installers, managing certificates, setting up CI/CD packaging, or publishing to the Microsoft Store.

Available today. Use it from your connected AI after setup.

Connect ahel once, and every AI you use reads what you have installed.

Then ask your AI: use the winui-packaging skill

What this skill tells your AI

The instructions your AI receives, as published by microsoft/win-dev-skills in plugins/winui/agent-plugin/skills/winui-packaging/SKILL.md and read by ahel’s review.

Quick Reference

TaskCommand
Build for release.\BuildAndRun.ps1 . -c Release --arch x64 --no-launch
Package + signwinapp package <dir> --cert devcert.pfx
Generate + sign + packagewinapp package <dir> --generate-cert --install-cert
Generate dev certificatewinapp cert generate
Trust certificate (admin)winapp cert install ./devcert.pfx
Sign existing filewinapp sign ./app.msix ./devcert.pfx
Self-contained deploymentwinapp package <dir> --cert devcert.pfx --self-contained

End-to-End Workflow

Step 1: Build for Release

Build the project in Release configuration without launching it. Use the BuildAndRun.ps1 wrapper from the winui-dev-workflow skill — plain dotnet build does not load the bundled Microsoft.WindowsAppSDK.Analyzers, so release builds would ship without the analyzer gate that development builds get:

.\BuildAndRun.ps1 . -c Release --arch x64 --no-launch

--no-launch builds and registers a development package without starting the app. Run winapp unregister before installing the signed .msix in Step 5, so the development registration does not conflict with the packaged identity.

Step 2: Generate Certificate (one-time)
winapp cert generate --manifest .

Creates devcert.pfx (default password: password). The --manifest flag auto-matches the Publisher field in Package.appxmanifest.

Step 3: Trust Certificate (one-time, requires admin)
winapp cert install ./devcert.pfx

Adds cert to machine Trusted Root store. Persists across reboots.

Step 4: Package and Sign
winapp package <build-output-dir> --cert ./devcert.pfx

This locates appxmanifest.xml, stages the layout, generates resources.pri, creates .msix, and signs it.

Step 5: Install or Distribute
# Local install
Add-AppxPackage ./MyApp.msix

# Or double-click the .msix file

Key Rules

  • Publisher must match between certificate and manifest Identity.Publisher — use winapp cert generate --manifest to auto-match
  • Prefer winapp package --cert over separate winapp sign — one step instead of two
  • cert install requires admin — run terminal as Administrator
  • Default PFX password is password — override with --password
  • --timestamp is critical for production — without it, signatures expire with the cert:
    winapp package <dir> --cert prod.pfx --timestamp http://timestamp.digicert.com
    
  • --self-contained bundles Windows App SDK runtime — larger but no runtime dependency

CI/CD with GitHub Actions

name: Build and Package
on: [push]
jobs:
  build:
    runs-on: windows-latest
    steps:
      - uses: actions/checkout@v4
      - uses: microsoft/setup-WinAppCli@v0.1

      - name: Build
        run: dotnet build -c Release -p:Platform=x64

      - name: Package
        run: |
          winapp cert generate --if-exists skip --quiet
          winapp package ./bin/x64/Release/ --cert ./devcert.pfx --quiet

      - name: Upload artifact
        uses: actions/upload-artifact@v4
        with:
          name: msix-package
          path: "*.msix"

CI/CD tips:

  • Use plain dotnet build on the runner, not BuildAndRun.ps1 — the wrapper registers a development package and needs the plugin's local analyzer payload, neither of which belongs in CI. Enforce analyzer coverage on the dev machine instead.
  • Use --quiet for clean output
  • Use --if-exists skip with cert generate to avoid failures on re-runs
  • Store production PFX as a repository secret

Store Submission

  1. Partner Center account — register at partner.microsoft.com
  2. Age ratings — complete the questionnaire in Partner Center
  3. Screenshots — capture at 1366x768 minimum resolution
  4. Privacy policy — required for apps that access internet or user data
  5. Submit: upload the signed .msix / .msixbundle produced by winapp package via Microsoft Partner Center — Apps and games → your app → Packages. Microsoft Store submission is browser-based; there is no first-party CLI submit command yet.

Troubleshooting

ErrorSolution
"Publisher mismatch"Run winapp cert generate --manifest to re-generate
"Certificate not trusted"Run winapp cert install ./devcert.pfx as admin
"Access denied"cert install needs admin elevation
"Certificate file already exists"Use --if-exists overwrite or --if-exists skip
"appxmanifest.xml not found"Run winapp init or pass --manifest <path>
"Package installation failed"Trust cert first; remove stale: Get-AppxPackage <name> | Remove-AppxPackage
Signature invalid after timeRe-sign with --timestamp

References

FileRead when...
references/sourcegen-patterns.mdSetting up AOT/trimming, JSON source generators, NativeAOT readiness, CsWin32

Signals

GitHub stars
433
Forks
32
Last commit
Sep 2026
Advanced
Catalog kind
skill
Gateway key
winui-packaging
Source
github.com/microsoft/win-dev-skills