👀 Be honest, when’s the last time you touched that Java 8 monolith or .NET Framework app? If the answer is “don’t make me,” you’re not alone. Those migrations can feel endless.

Here’s the good news: GitHub Copilot app modernization for Java and .NET is now generally available, turning migrations you’ve been avoiding for years into week-long sprints.

You can now scan your codebase, generate a migration plan, apply code fixes, validate with tests, and ship to Azure, all inside VS Code or Visual Studio.

How it works:

1. Scan: Analyze your codebase, dependencies, and what needs upgrading.
2. Plan: Get a step-by-step migration plan you can edit.
3. Execute: Apply code updates and dependency fixes.
4. Validate: Run tests, catch vulnerabilities, and confirm builds.
5. Deploy: Containerize your app and ship it to Azure.

And all this is guided by Copilot agent mode, so you’re reviewing and approving, not stuck in dependency hell. 😈

From upgrade plan to passing tests in one agent session. Notice the "LOW" risk assessment and production-ready next steps on the right.

Real world wins

Teams are already using Copilot app modernization to:

• Upgrade Java (8 → 11 → 17 → 21) and migrate Spring Boot apps to Azure.
• Move .NET Framework projects to .NET 8/9.
• Swap legacy auth for Microsoft Entra ID (cloud-ready security, no manual rewiring).
• Containerize apps and provision infra, without writing Terraform by hand.

We’re not talking just demos but actual migrations, done in days.

Migration complete: four files modified, zero vulnerabilities, all tests passing. Notice the validation results on the right.

Try it now

Java developers:

• Install the GitHub Copilot app modernization – upgrade for Java extension in VS Code.
• Open your project, start an agent session, and tell it what you want to upgrade.
• Watch the end-to-end video walkthrough.

.NET developers:

• Open your project in Visual Studio 2022 (17.14.16 or later).
• Right-click your solution and select Modernize or use @modernize in Copilot Chat.
• Follow the .NET setup guide and video intro.

Why it matters

Legacy code isn’t going anywhere by itself. Copilot handles the grunt work of scanning dependencies, fixing deprecated APIs, and running tests in a loop until they pass. You still make the calls. You still review the code. But you’re not burning days on build errors.

Legacy code isn’t just a skill issue, it’s a time issue. Copilot helps on both fronts, speeding up your workflow and making sense of code that’s hard to untangle.

Here’s to faster fixes and smoother releases!

Read our full guide to modernizing Java projects with Copilot

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✨ This newsletter was written by Andrea Liliana Griffiths and produced by Gwen Davis. ✨

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