How to Migrate ASP.NET Core Applications to .NET Core 8: Tutorial

Key Benefits of Moving to .NET 8

.NET 8 brings three essential things. Long-term support, better performance and a smoother overall development experience. Have you ever dealt with slow startup times or oversized Docker images? .NET 8 takes big steps toward solving them.

Are you thinking about dot net application migration services development company? Moving to ASP.NET Core 8 is one of the most straightforward ways to get measurable gains.

Here’s why teams actually migrate:

Long-Term Support Without Stress. Later versions of .NET give you stability for years. No rushed upgrades, no last-minute security patch emergencies.
Faster Applications. The runtime, GC, networking stack and ASP.NET Core pipeline all got serious performance upgrades. Your app will feel snappier even before you start optimizing anything.
Native AOT That Actually Helps. For microservices, worker services, serverless apps or small utilities, Native AOT means tiny binaries and instant startup. It’s a game-changer.
Cleaner Application Setup. Minimal hosting is now the “normal” way to configure apps.
C# 12 keeps code shorter and safer. If your codebase still feels “a little .NET Framework,” this is a breath of fresh air.
Cloud-Ready by Default. Smaller Docker images, faster cold starts and better diagnostics make .NET 8 ideal. If you are targeting Kubernetes, AWS, Azure, or containerized environments, it is perfect.

In short: a .NET Core 8 gives you speed, safety and a platform you can confidently build on.

Before You Start: What to Check

Before you jump into the migration, slow down and look around. Here’s what every team should check (and what most teams skip at first):

Make sure your tools are ready

Before any migration, ensure your development environment is fully prepared. Install the .NET 8 SDK and update your IDE so they can properly handle ASP.NET Core 8 projects. Old tools or extensions can cause confusing errors that look like migration issues. But they are really environmental problems. Spending five minutes here can save you hours of troubleshooting later.

Create a separate migration branch

Always isolate migration work in its own branch. This keeps your main branch stable and lets your team continue delivering features without disruption. It also provides a safety net. If something goes wrong, you can revert or re-run the migration without affecting production code. Think of it as your “experimental lab” where you can break things safely.

Audit dependencies

Dependencies are where most migration surprises live. Some NuGet packages simply don’t support .NET 8 or ASP NET Core 8 yet. Others require major-version upgrades that may introduce breaking changes. Identify outdated or abandoned libraries early, so you have time to replace them. This step alone can make your migrate to .NET Core 8 process dramatically smoother.

Review Microsoft’s breaking changes

Every major .NET release introduces changes that may impact your codebase. Especially in ASP.NET Core, EF Core, Identity, serialization, logging, and hosting. Don’t rely on guesswork. It is more efficient to read the official breaking changes to understand what might fail after the upgrade.

This helps you avoid unexpected runtime errors and confusing behavior during testing. It’s one of the least glamorous but most essential steps in a successful .NET Core 8 update.

Check your architecture

If you’re preparing to migrate from .NET Framework to .NET Core 8, this step is critical. Framework-era code often contains legacy APIs or patterns that won’t survive the jump without refactoring.

This quick checklist will save you hours (and sanity) once migration begins.

How to Migrate Your App: Step by Step

Here’s the version that developers actually follow:

Step 1 – Audit and update all dependencies

Before touching the target framework, ensure:

NuGet packages have versions that support .NET 8
EF Core version can be upgraded
Middleware and 3rd-party components have .NET 8-compatible releases
No abandoned packages are blocking the upgrade

This is the stability step. You cannot migrate to .NET 8 cleanly without doing this first.

Step 2 – Set up your environment

Install the .NET 8 SDK to ensure a consistent environment. Don’t forget to make a full backup of your code. And prepare configuration files, tools, and environment variables for the upgrade. This preparation removes obstacles later in the process.

Step 3 – Update project files and SDK version

Once your environment is ready, switch the project’s target framework to .NET 8. Update any global configuration files to reflect the new version. Make sure build scripts, tooling and analyzers pick up the updated SDK. This step sets the groundwork for the code and dependency updates that follow.

Step 4 – Adjust code for breaking changes

Once you update everything, you might see a few build errors pop up. That is normal. Fix anything related to API changes, deprecated features or old hacks your app no longer needs in ASP.NET Core 8. Take a look at your config, logging, serialization, auth, and DI patterns. Make sure they follow the modern .NET 8 way.

Step 5 – Test everything

Run all your automated tests and add performance or load tests to confirm .NET 8 didn’t introduce any regressions. Double-check auth flows, API behavior, serialization formats, and anything that touches your database. Think of this step as your safety net before you even think about staging or production.

Step 6 – Deployment preparation

Make sure your Dockerfiles and CI/CD pipelines all point to .NET 8. Check that every environment is configured for the new runtime. Do a full practice deployment in staging to catch environment-specific surprises early. If everything behaves there, you’re in great shape for a smooth production rollout.

Step 7 – Monitor and optimize

Monitor logs, metrics to catch any runtime anomalies early. Tune your application’s runtime settings and memory usage to take advantage of .NET 8’s performance improvements. Document the migration steps, lessons learned, and any updated procedures for your team. A clean post-migration review ensures the next upgrade will be even smoother.

Common Issues (And How to Solve Them)

Every migration has a few bumps. Here are the ones developers hit most often:

“This package doesn’t support net8.0.”

Solution: update it or replace it. There is usually a modern alternative.

Hosting model confusion

If Startup disappears, don’t panic. Just move your config and middleware setup into the new Program.cs pattern.

EF Core query changes

If a query runs differently, inspect the generated SQL. Most issues come from behavioral changes in LINQ translation.

Authentication changes

Identity, JWT handlers, and cookie auth occasionally require updated configuration.

JSON serialization surprises

System.Text.Json evolves over time. If your API depended on old defaults, update your global json options.

Removed APIs

This is normal in long-term modernization. Replace old utility classes and helpers with their modern equivalents.

Nothing here is dramatic. It’s normal cleanup work during any serious upgrade.

Conclusion

Migrating to .NET 8 helps modernize your entire application ecosystem. Planning a small ASP.NET Core 8 update or a full migration from .NET Framework to .NET Core 8? The benefits are real. Faster performance, stronger security, easier maintenance.

If your team needs guidance or full support, a dot net application migration services development company can help. This will accelerate the process and reduce risks.