he launch of .NET 10 brings innovation, improved performance, and new developer-friendly tools. However, alongside these enhancements come breaking changes in .NET 10 — updates that may disrupt existing applications if not carefully managed.
For enterprises, startups, and seed-funded companies that rely on .NET for mission-critical systems, preparing for these changes is essential.
In this blog, we’ll explain what breaking changes are, highlight the most important updates in .NET 10, and share practical steps for a successful migration.
What Do Breaking Changes in .NET 10 Mean?
A breaking change is any modification in the runtime, compiler, or framework that causes:
- Compile-time failures (such as removed or renamed APIs).
- Runtime errors due to altered behavior.
- Different application results compared to earlier versions.
These changes are introduced to improve security, consistency, and performance. Still, they can significantly impact enterprise applications if not addressed during an upgrade to .NET 10.
Categories of Breaking Changes in .NET 10
When planning an enterprise app migration to .NET 10, you should be aware of breaking changes across multiple categories:
1. Runtime Behavior Adjustments
Altered runtime execution may change how applications behave in certain scenarios.
2. API Removals and Modifications
APIs marked as [Obsolete] in .NET 8 and .NET 9 are now removed. Codebases depending on them must migrate to modern alternatives.
3. Compiler and Language Updates
C# 13 introduces stricter compiler rules that may generate new warnings or errors.
4. Framework and Library Changes
ASP.NET Core, EF Core, and system libraries have been updated, potentially impacting business logic and workflows.
5. SDK and Tooling Updates
Project templates, build configurations, and SDK tooling are updated in .NET 10 migration, requiring CI/CD adjustments.
Key Breaking Changes in .NET 10
Here are some of the most impactful changes enterprises need to prepare for:
- Default Encoding Update – Certain APIs now use UTF-8 by default, affecting file handling and serialization.
- Obsolete API Removal – Legacy APIs flagged in earlier versions are no longer available.
- ASP.NET Core Pipeline Refinements – Middleware execution order and request handling are more strict, affecting custom pipelines.
- EF Core Compatibility Changes – Updated query translation behaviors may alter application results.
- Nullable Reference Enforcement – Stricter compiler enforcement of nullable reference types introduces new warnings.
- Performance-Driven Modifications – Some APIs have been redesigned for better performance, potentially impacting edge-case functionality.
Preparing for a Smooth .NET 10 Migration
To reduce risks and ensure a successful upgrade to .NET 10, enterprises should:
- Review Release Notes – Study Microsoft’s official .NET 10 migration guide and documentation.
- Run Extensive Testing – Perform unit, integration, and regression tests to detect issues early.
- Enable Roslyn Analyzers – Use analyzers and nullable reference warnings to identify potential problems.
- Adopt Incremental Upgrades – Upgrade step by step rather than skipping multiple versions.
Common Mistakes During Migration
Organizations often face challenges because of:
- Ignoring deprecation warnings in earlier releases.
- Assuming runtime behavior remains unchanged.
- Neglecting third-party dependency updates.
- Upgrading without proper environment testing.
- Overlooking nullable reference type enforcement.
Real-World Enterprise Example
A financial services company migrating from .NET 8 to .NET 10 encountered challenges due to EF Core API removals and stricter nullable checks.
They achieved a successful migration by:
- Enabling analyzers early.
- Rolling out features gradually with feature flags.
- Running phased deployments with thorough regression testing.
This approach reduced downtime and ensured system stability.
Conclusion
The breaking changes in .NET 10 may seem disruptive, but they pave the way for improved security, performance, and long-term stability.
By reviewing official documentation, running comprehensive tests, leveraging analyzers, and adopting incremental upgrades, enterprises and startups can achieve a seamless .NET 10 migration.
When planned correctly, upgrading ensures your applications remain future-ready while unlocking the full potential of .NET 10.
Additional Resources: