Modernize .NET applications in the GitHub Copilot app

Mika Dumont

Senior Product Manager

Upgrading a .NET application isn’t a single prompt.

Every upgrade begins with understanding your application, evaluating dependencies, planning the work, applying code transformations, fixing build failures, and validating the results. Each phase uncovers new information that shapes the work that follows. A dependency update can uncover compatibility issues, a build failure can change the next task, and dependencies between projects can change the order of work.

GitHub Copilot upgrade carries out that workflow. The GitHub Copilot upgrade agent assesses your application, generates a structured upgrade plan, creates implementation tasks, and executes the work.

Now you can follow that workflow in the GitHub Copilot app through an interactive upgrade canvas. Instead of piecing together progress across chat, generated Markdown artifacts, and code changes, the upgrade canvas gives you a live view of the modernization workflow as it unfolds.

The result is a .NET modernization experience that’s easier to follow, easier to review, and easier to steer.

From assessment to execution

The GitHub Copilot upgrade agent starts by assessing your .NET application and identifying what needs to change:

What version of .NET is this application targeting?
Which NuGet packages need to be updated?
Are there breaking API changes?
Which projects can be upgraded independently?
What should happen first?

From there, the agent generates a structured upgrade plan and breaks the work into actionable implementation tasks. As execution begins, the canvas reflects the latest state of the upgrade, including the assessment, upgrade plan, implementation tasks, execution progress, code changes, build failures, and final results.

Instead of asking the agent to summarize what happened or piecing together progress from generated artifacts, you can follow the modernization effort from assessment through execution in a single view.

Available wherever you work

While the GitHub Copilot app provides the interactive upgrade canvas, GitHub Copilot upgrade is also available across the developer tools you already use:

Visual Studio – Built directly into Visual Studio. Right-click your solution or project in Solution Explorer and select Modernize to start a .NET upgrade.
Visual Studio Code – Install the GitHub Copilot upgrade extension, select the Upgrade agent from the agent picker dropdown, and prompt it to modernize your .NET application.
GitHub Copilot CLI – Install the GitHub Copilot upgrade plugin to assess, plan, and execute .NET upgrades directly from the terminal.

Whether you prefer working in an IDE, the terminal, or the GitHub Copilot app, you can use the same upgrade workflow across every surface.

Get started

Getting started takes just a few clicks.

Add the GitHub Copilot upgrade marketplace. If you don’t already have the GitHub Copilot app installed, you’ll be prompted to install it first.
In the Add plugin marketplace? dialog, select Allow to add the microsoft/upgrade-agent-plugins.
In the Plugins window, select Add marketplace.
Select Install for the upgrade-agent plugin.
Open your repository, start a new agent session, and select the Upgrade agent from the agent picker dropdown.

To open the interactive upgrade canvas:

In the upper-right corner of the GitHub Copilot app, select the review panel icon (Toggle review panel).
In the review panel, select + (Open in panel).
Choose Upgrade Dashboard.

The Upgrade Dashboard opens an interactive upgrade canvas where you can assess your application, review the upgrade plan, track execution, and monitor your modernization effort from start to finish.

Try it on your next .NET upgrade, and share your feedback or ideas in the GitHub Copilot upgrade repository.

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Author

Mika Dumont

Senior Product Manager

Mika is a Product Manager on the .NET and GitHub Copilot developer experience.

2 comments

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Michael Taylor 16 minutes ago

Having just tried this tool, yet again, to upgrade a NET Framework to NET Core web API I still think it is pretty bad experience. Let's start with the enormous amount of markdown files it generates for planning, every task, etc. Every single one of these opens in the VS editor and you have to approve it. It is overwhelming and slow.

Moving on to the actual upgrade it really struggles to do even simple things. Upgrading a class library is straightforward and it rarely has issues. But once it hits the ASPNET/Core projects it struggles. It can generate a boilerplate...
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Having just tried this tool, yet again, to upgrade a NET Framework to NET Core web API I still think it is pretty bad experience. Let’s start with the enormous amount of markdown files it generates for planning, every task, etc. Every single one of these opens in the VS editor and you have to approve it. It is overwhelming and slow.

Moving on to the actual upgrade it really struggles to do even simple things. Upgrading a class library is straightforward and it rarely has issues. But once it hits the ASPNET/Core projects it struggles. It can generate a boilerplate project and copy over basic things like models and controllers but everything else it either spins forever or just doesn’t do anything. In my last attempt where I was using Autofac in NF I told it in the rules to use the NC DI stuff. It couldn’t figure it out and left Autofac in there. It also used the System.Web adapters after it confirmed my instructions to not use them. The plan said not to and it did anyway. Migrating from web.config to appsettings still proves to be manual.

Package management is also problematic. It can upgrade existing packages but isn’t smart enough to figure out that some packages aren’t needed/supported and should be replaced. It just keeps trying anyway. You get into an endless loop of “continue”, wait for it to fail, tell it how to proceed, wait for it to fail. Or, even worse, “continue” upgrade, let it run for a while and then it decides it needs to prompt you to continue again. It doesn’t seem work related. I just want a “upgrade everything and don’t prompt me until done” but it can’t do that so I have to babysit it. If you go through enough of these then it eventually stops responding and you basically have to kill the editor.

It also wants to build and run tests as it goes along but it is in the middle of a migration so build/tests will fail. Yet it wants to fix them before continuing even if you tell it not to. Towards the end of my last attempt it was trying to build, which will fail, got some unexpected error and permanently locked the session. I had to kill the editor and I lost all the changes it hadn’t committed yet. Hours down the drain.

It might be useful for getting boilerplate projects migrated but honestly it is still faster and easier to just manually upgrade. We do all the same steps as the tool but we don’t have to waste time on useless cycles or trying to explain the process to ourselves. We know what needs to happen, why can’t the AI just do what we wanted.

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- Mika Dumont Author 15 seconds ago
  
  Thanks for taking the time to share such detailed feedback.
  
  I'd love to learn a bit more about your setup. Which version of Visual Studio were you using, and which model did you have selected for the upgrade? I'm especially interested in the ASP.NET/Core migration scenarios you mentioned, since that's an area we're continuing to improve.
  
  If you remember any of the prompts or instructions you gave the agent (especially around Autofac and avoiding System.Web adapters), I'd be interested in seeing those as well. Understanding where the agent didn't follow your intent helps us improve the experience.
  
  And if you can reproduce the...
  Read more
  Thanks for taking the time to share such detailed feedback.
  
  I’d love to learn a bit more about your setup. Which version of Visual Studio were you using, and which model did you have selected for the upgrade? I’m especially interested in the ASP.NET/Core migration scenarios you mentioned, since that’s an area we’re continuing to improve.
  
  If you remember any of the prompts or instructions you gave the agent (especially around Autofac and avoiding System.Web adapters), I’d be interested in seeing those as well. Understanding where the agent didn’t follow your intent helps us improve the experience.
  
  And if you can reproduce the issue where the session became unresponsive or you lost changes, please consider reporting it through Visual Studio’s Report a Problem tool or opening an issue in the GitHub Copilot upgrade repository. The logs from those reports are incredibly helpful for investigating issues like that.
  
  Thanks again for the feedback.
  
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