Skip to main content

From ClickOnce

Applies to
Windows
MacOS
Linux

Migrate ClickOnce to Velopack.

warning

This is a relatively untested guide written with community feedback. If you have run into any issues which can improve the docs please submit a PR or issue.

It is not a straight-forward migration, since clickonce apps are very different to Velopack. The high level process overview is something like:

  • Ship a ClickOnce update which downloads and runs your Velopack app.
  • When the Velopack app starts, uninstall your ClickOnce app.

Your First Velopack Release​

We will need to start by publishing your first Velopack release.

  1. If you are using any of the ApplicationDeployment API's to check for updates, you will need to remove them.
  2. Turn off ClickOnce updates in your project settings, then manually open the .csproj and remove all ClickOnce related properties.
    tip

    If you are still on the legacy msbuild/csproj format, you should consider migrating to the SDK style project using the dotnet/upgrade-assistant (The VS extension is also very easy to use). You can continue to use .Net Framework, and the legacy csproj format may work, however is not officially supported by Velopack so an upgrade is recommended.

  3. Follow the Velopack C# QuickStart guide and/or review the samples to add Velopack updates to your application.
  4. Your first install of Velopack should uninstall your ClickOnce app. Ideally we would just run the default uninstaller, but since it cant be used unattended/silent, we need to include the Wunder.ClickOnceUninstaller code. It is not currently distributed on NuGet, so you may wish to download and include the code directly in your project.
  5. Once ClickOnceUninstaller is added to your project, we can add a Velopack hook which uninstalls your clickonce app. You should already have VelopackApp in your main method at this point, and you'll need to modify it so that we add the clickonce uninstall code on Velopack install: 
    VelopackApp.Build()
        .WithAfterInstallFastCallback((appVersion) =>
        {
            var uninstallInfo = UninstallInfo.Find("Application Name");
            if (uninstallInfo == null)
            {
                var uninstaller = new Uninstaller();
                uninstaller.Uninstall(uninstallInfo);
            }
        })
        .Run();
    Make sure you test this code independently to verify that it can uninstall your clickonce app successfully before moving on.
  6. 🎉 Compile your app and build your first release with vpk pack. You should see YourAppSetup.exe and some other files. We're now ready to ship a ClickOnce update which downloads and runs the Velopack setup.

Your Last ClickOnce Update​

The code in your final ClickOnce update will just install YourAppSetup.exe that we created in the previous section and will be fairly straightforward.

  1. You will likely want to bundle YourAppSetup.exe into your application as an embedded resource.
  2. On startup (eg. Main method), you may wish to show a dialog/message to the user to let them know you are about to migrate/update the app.
  3. Then, extract YourAppSetup.exe to a temporary location (eg. the user downloads folder) and run it. If you wish this to be invisible, you can add the YourAppSetup.exe --silent arg. Otherwise, if you omit this argument the user will be shown a progress dialog.
  4. As soon as you've run YourAppSetup.exe you should quit your application, either by return 0; from Main() or via Environment.Exit(0). Once your Velopack has installed, it will delete this app.
    tip

    To reduce the size of your ClickOnce app, you may wish to delete any unused code/dependencies in this update. Since the only purpose of this update is to run the Velopack installer, any code/dependencies which does not serve this purpose is just extra time/delay for the user.