Deploying a Qt App to the Microsoft Store with CPack and MakeAppx

Posted on August 15, 2025

As the maintainer of an open source Qt application, I’ve run into a common problem: Windows users often get blocked by security warnings because the software isn’t digitally signed. The cost of a code signing certificate can be prohibitive, but there’s a fantastic alternative — the Microsoft Store. By submitting your app to the Store, Microsoft signs it for you, eliminating trust warnings and giving users a clean, familiar installation experience.

This guide explains how I replaced my Windows NSIS installer with a Microsoft Store–ready package. The Store doesn’t want a classic installer — it wants an .appxupload file. Fortunately, Qt already works with CMake and CPack, so we can swap out the CPack generator and use MakeAppx.exe to produce a Store package without rewriting the build system.

Here’s the workflow I used to go from an NSIS-based .exe to a Store-ready .appxupload with minimal effort.

1. Prerequisites

You’ll need:

2. Adjusting CMakeLists.txt for CPack

If you were using NSIS before, you might have had something like:

set(CPACK_GENERATOR "NSIS")

We’re going to replace it with:

set(CPACK_GENERATOR "External")

Why External? Because the Microsoft Store packaging process is not handled by a built-in CPack generator. Instead, we instruct CPack to run a custom script that orchestrates the entire packaging workflow. This script finds all the necessary files and uses the MakeAppx.exe utility to build the final package.

Reference this commit to see all of the necessary changes to invoke the MakeAppX.cmake external script: https://github.com/MUME/MMapper/commit/a86804cc6c1f57eae272a181d4e474574ea248d4

3. Submitting to the Microsoft Store

Once you have your .appxupload:

  1. Go to Partner Center

  2. Create a new app or update an existing one

  3. Upload your .appxupload file

  4. Fill in your Store listing and submit for certification

Microsoft typically takes about a week to approve a new submission. Once approved, you can follow the same process for updates, and they’ll appear automatically for all users.

4. Why This Approach Wins

This process solves two of the biggest headaches for open source Windows projects:

  1. No expensive code signing certificate — The Store signs the app for you, so users never see a “publisher unknown” warning.

  2. Automatic updates — The Store handles seamless upgrades, keeping all users on the latest version without any manual downloads or installers.

Once I understood the flow, the transition from NSIS to a successful Store submission took less than a week. The result: a trustworthy install process for users, less maintenance for me, and a deployment pipeline that’s future proof– if still a bit manual on the submission portion.

Tags: qt appx msix cmake cpack