Migration to the Latest .NET Versions: Best Practices

Applications written in old code at some point become slow. They are no longer able to meet the requirements of today’s users. Such an architecture might not handle modern workloads and integrations. Also, security becomes a critical issue.

Users expect fast performance and consistent reliability across devices. These are standards that old applications often cannot meet. So, businesses conclude that migration is needed to stay competitive.

But the process is risky. It requires careful planning. In this article, we are exploring best practices to help you migrate to the latest version of .NET.

Why Migrate to the Latest .NET Versions?

Microsoft is working on .NET, so it gets new features and enhancements regularly. The platform has long- and short-standing versions. It means that companies need to upgrade their applications regularly too.

Maintaining the versions is important when a business wants performance and new features. Migration helps cut potential losses a business might experience because of outdated software. Legacy applications can cause problems, damage a company’s reputation and frustrate users.

But here are the reasons to migrate:

• Improved performance. The latest versions of .NET bring faster execution times. This is thanks to optimizations in JIT compilation. Also, reduced memory usage, enhanced garbage collection and better scalability.
• Enhanced security. Newer versions of .NET usually have vulnerabilities patched. Microsoft has also been working on improving encryption and authentication features. The company adds support for modern security standards.
• Compatibility with modern technologies. New .NET versions have better integration with cloud services. Also, they support microservices and serverless architectures.
• Saved costs. Running on old .NET versions can lead to higher maintenance costs. And newer versions are optimized for cost efficiency.

Overall, newer .NET versions provide better performance. They save costs, support cross-platform development, and are compliant with regulatory requirements. Apps with higher performance mean that users are more satisfied working with them. This might potentially lead to more sales.

Understand .NET Versioning and Support

For effective migration, you need to understand .NET versioning and support. .NET has a release pattern:

• versions with an even number (.NET 6 or .NET 8) are created as Long-Term Support (LTS) releases, with 3 years of support.
• versions with odd numbers (.NET 7 or .NET 9) are Standard-Term Support (STS) releases with 18 months of support.

If you understand this, you can plan the project lifecycles and maintenance easily. When the version reaches its end-of-life, Microsoft no more updates its security. This makes it essential to migrate to supported versions.

Now, .NET 8 is supported until November 10, 2026. And .NET 9 is the latest STS release. Microsoft supports it until May 12, 2026. The latest version is .NET 10. It was released in 2025.

Developers should regularly check Microsoft’s official .NET support policy. They will be able to plan their upgrades accordingly.

Assessing Your Current .NET Application

When planning app migration, you need to analyse your current .NET application. The analysis usually includes identifying dependencies and breaking changes and analyzing infrastructure compatibility.
Identifying dependencies and analyzing code can help you avoid breaking changes. Check for outdated libraries or NuGet packages. They might not support newer versions of .NET. As a result, the app can crash or cause unexpected behavior.

Also, use tools like .NET Upgrade Assistant as it helps you find breaking changes. Besides this, tools help automate analysis, which reduces manual effort and saves time.

Another important thing is that your environment supports the latest .NET version.

Choosing a Migration Strategy

There are several migration strategies you can choose from. The choice depends on your goals and available resources:

In-Place Upgrade vs. Side-by-Side Migration

An in-place upgrade changes the existing codebase to the target .NET version. It is simpler for small projects, with minimal dependencies. With this migration strategy, there is no need for the maintenance of two app versions. So you don’t spend a lot of resources on parallel infrastructure.

But in-place upgrade has a high risk of downtime. It is not suitable for enterprise-level applications.

With side-by-side migration, you create a new project alongside the legacy app. Developers gradually migrate components to the new project and maintain the old one. This strategy is safer for large monolithic applications with complex dependencies.

Incremental vs. Big Bang Approach

When you opt for an incremental migration, you upgrade your application component by component. Here, you are supposed to use feature flags or compatibility shims to isolate changes.

This approach allows you to avoid risks, as issues in one component don’t block progress on others. This means that different teams can work on different parts.

Incremental migration is suitable for large and modular apps.

The Big Bang migration approach means upgrading the entire application at once. It requires freezing feature development during the process. This strategy is faster for small-to-medium apps. But it comes at a high risk, as one single error might derail the whole project.

Factor	Recommended Migration Strategy	Notes
Project Size	Small apps -> In-Place + Big-BangLarge apps -> Side-by-Side + Incremental	Larger projects benefit from gradual migration to reduce risks.
Risk Tolerance	Risk-averse? -> Prioritize Incremental or Side-by-SideNeed speed? -> Big Bang for simple apps	Higher risk means more testing and fallback plans.
Team Capacity	Incremental -> Sustained effort over timeBig Bang -> Needs concentrated resources	Consider developer availability and workload.
Business Impact	Avoid downtime? -> Side-by-side is safer	Choose an approach that minimizes disruption

Preparing for Migration

Before migrating your app, set up a testing environment. You will need to confirm changes and cut risks. You can use feature flags to toggle between old and new versions of your application.

Use code refactoring for future-proofing and security. Replace deprecated APIs and use modern C# features like records and async/await. For example, you can replace WebClient with HttpClient, which supports async/await.

Furthermore, automate the process with CI/CD pipelines. This helps you ensure reliable builds, testing, and deployment.

Migration Execution

During the migration process, upgrade project files to the latest SDK-style format (.csproj). Remove all outdated dependencies and frameworks. Also, update dependency injection to resolve breaking changes.

Finally, run performance benchmarks with BenchmarkDotNet. This is necessary to compare app performance before and after migration.

Testing and Validation

After migration, it is critical to test and validate what you’ve received. As a new .NET version might behave differently, you need to conduct tests. This is necessary to ensure that the existing logic still works.

Also, conduct performance and load testing to confirm scalability. This is especially necessary for apps that experience traffic spikes. You can use tools like k6, JMeter, or Azure Load Testing.

And perform security audits to enforce HTTPS, validate authentication and access controls. Check for vulnerabilities in updated dependencies.

Deployment and Post-Migration Considerations

For a smooth deployment, use gradual rollout strategies. For example, canary releases or blue-green deployments. These strategies help minimize risk and avoid massive issues. You roll out changes to a small group of users or a parallel environment. And if the issues happen, they affect fewer users.

Enhance observability with Application Insights, OpenTelemetry, or Prometheus. Setting up alerts for crashes or performance drops can also help. You will be able to detect anomalies and failures before users notice.

Conclusion

Migrating to the latest .NET version doesn’t have to be overwhelming. Stay up-to-date with .NET release cycles to keep your application secure and performant.

If you need expert support, Softacom’s migration services make the process smoother. We combine AI-powered tools with expert oversight. Reach out to us.