THE .NET 8/9 TO .NET 10 MIGRATION GUIDE: Upgrade ASP.NET Core, Entity Framework, Blazor, Containers, CI/CD, and Production Services Before Support Ends

Upgrading to .NET 10 is easy when the application is small, the database is disposable, and production does not matter.

Real systems are different.

A production migration can fail even after the solution builds successfully. Authentication may behave differently. EF Core may generate different SQL. A container may start locally but fail in production because of native dependencies, certificates, Linux image changes, or configuration. Background services may start differently. CI may quietly use the wrong SDK. A database migration may succeed in development and still be unsafe to deploy.

The .NET 8/9 to .NET 10 Migration Guide is a practical, production-focused handbook for developers and engineering teams who need to move existing applications to .NET 10 without turning the upgrade into an uncontrolled rewrite.

Rather than treating migration as “change the target framework and fix compiler errors,” this book follows the complete engineering path:

Inventory → Baseline → Toolchain → Retarget → Dependencies → Compilation → Behavioral Compatibility → Database → Deployment → Validation → Production Cutover

You will learn how to:

• assess a .NET 8 or .NET 9 application before making changes;

• control the .NET 10 SDK with global.json and CI;

• retarget projects to net10.0 without unnecessary package churn;

• identify breaking changes that do not produce compiler errors;

• migrate ASP.NET Core hosting, middleware, authentication, OpenAPI, static assets, and proxy behavior;

• upgrade EF Core while validating providers, migrations, generated SQL, query behavior, and production database safety;

• migrate Blazor applications across SSR and interactive rendering scenarios;

• rebuild Docker images and validate Linux base-image, OpenSSL, certificate, permission, and native dependency changes;

• update CI/CD so the pipeline, not the developer machine, proves the migration;

• test background services, scheduled work, cancellation, shutdown, and dependency failures;

• compare performance before and after migration instead of assuming .NET 10 must be faster;

• exercise failure paths such as database outages, API failures, expired certificates, container termination, and failed migrations;

• choose between rolling, blue/green, canary, and scheduled production cutovers;

• define rollback conditions before production pressure makes the decision for you;

• remove temporary .NET 8/9 compatibility scaffolding after stabilization;

• establish a sustainable .NET 10 servicing routine.

The book repeatedly separates required migration work from optional modernization, helping you keep the number of moving parts under control.

Its guiding principle is simple:

Migrate first. Modernize deliberately.

This is not a “What’s New in .NET 10” catalogue, and it is not a beginner introduction to .NET, Docker, EF Core, or CI/CD.

It is for working developers who already know those technologies and need a disciplined way to move a real application to .NET 10, prove that it still behaves correctly, deploy it safely, and recover if production disagrees.

A successful migration is not one where the compiler is satisfied.

It is one where the application, database, infrastructure, deployment pipeline, observability, and rollback path have all been demonstrated on .NET 10.