.NET Framework to .NET Core

Migrating a .NET Framework application to .NET Core is a big step towards modernizing your software. It offers several advantages, such as better performance, the ability to run on multiple operating systems (Windows, Linux, and macOS), and improved security through regular updates from Microsoft. Studies show that more than 60% of businesses are shifting to .NET Core to update their old applications and stay ahead in the competitive market.

However, migrating is not just about moving the code. It needs careful planning, checking compatibility, updating dependencies, and testing thoroughly to ensure everything works smoothly. In this detailed guide, we will walk you through the step-by-step process of migrating your .NET Framework application to .NET Core.

Step 1: Assess Your Application

Before you start, you need to analyze your existing .NET Framework application to understand what challenges you might face and whether it is even possible to migrate your application without too many issues.

Key Points to Assess:

Dependencies: Identify all third-party libraries and NuGet packages used in your application. Some packages may not be supported in .NET Core, so you will need to find alternatives.
APIs: Check the APIs and features your application is using. Some older APIs are not available in .NET Core, so you may need to rewrite certain parts of the code.
Target Framework: Find out which version of the .NET Framework your application is running on. This will help you decide the best .NET Core version for migration.

Project Type: Some application types require extra steps to migrate. For example:

- Windows Forms and WPF applications are supported only in .NET Core 3.1 and later.
- ASP.NET MVC and Web API applications are better suited for migration to ASP.NET Core.
Platform-Specific Code: If your application has platform-specific code (e.g., Windows-only code), you may need to change it or find alternatives to ensure it works on Linux and macOS as well.

Pro Tip: Use the .NET Portability Analyzer tool to check how much of your application’s code is compatible with .NET Core. This tool provides a report on what needs to be changed before migration.

Step 2: Prepare for Migration

Once you assess your application and determine that migration is possible, you need to prepare for the process.

Backup Your Project

Before making any changes, create a full backup of your application. This includes:

Source code files
Configuration files (Web.config, App.config, etc.)
Any related assets or database files

Dependencies and external libraries

Having a backup ensures that you can restore the old version if anything goes wrong during migration.

Upgrade Dependencies

Update all third-party libraries and NuGet packages to their latest versions.
Check whether these dependencies support .NET Core. If not, find alternative libraries that provide similar functionality.
If a certain library is essential and has no .NET Core equivalent, you may need to write custom code to replace its functionality.

Step 3: Convert the Project File

.NET Core uses a new SDK-style project format that is simpler and more flexible than the older format used in .NET Framework.

Steps to Convert:

1. Create a New .NET Core Project

Use Visual Studio or the .NET CLI to create a new .NET Core project. Run the following command:

dotnet new <project-type> -n <project-name>

Replace <project-type> with the type of your application (e.g., console, mvc, webapi).

2. Copy Code Files

Move all your C# (.cs) or VB (.vb) files from the old .NET Framework project to the new .NET Core project.

3. Update the Project File

Manually update the .csproj file in the new project to include necessary dependencies and frameworks.

4. Remove Unused References

.NET Core does not support certain old libraries (like System.Web). Remove these references and replace them with .NET Core alternatives.

Step 4: Update Code for .NET Core

Replace Unsupported APIs

Some APIs used in .NET Framework are not available in .NET Core. You need to replace them with supported alternatives.
Example: If you are using HttpContext.Current, replace it with IHttpContextAccessor in ASP.NET Core.

Configuration Changes

Move from Web.config or App.config to appsettings.json.
Use Microsoft.Extensions.Configuration for managing configuration settings in .NET Core.

Logging

In .NET Core, use Microsoft.Extensions.Logging, which is the recommended logging framework.

Step 5: Test the Application

Testing is a crucial step to ensure that everything is working correctly after migration.

Unit and Integration Testing

Run all unit tests and integration tests.
Update tests to match changes made during migration.

Manual Testing

Run the application manually and check if it behaves as expected.
Pay extra attention to areas where major changes were made.

Step 6: Deploy the Application

Once everything is tested and working fine, you can deploy your application.

Deployment Options:

Framework-Dependent Deployment (FDD): Requires .NET Core runtime to be installed on the server.
Self-Contained Deployment (SCD): Bundles the .NET Core runtime with your application so it runs without external dependencies.

Steps to Deploy:

Publish your application using the .NET CLI:

dotnet publish -c Release

Bonus Tips for a Smooth Migration

Adopt Incremental Migration

If your application is large, migrate it in phases instead of all at once.
For example, start with small modules or services and gradually move everything to .NET Core.

Use .NET Standard Libraries

If you have shared libraries, convert them to .NET Standard. This makes them compatible with both .NET Framework and .NET Core.

Leverage Containers

Use Docker to containerize your .NET Core application for easier deployment and better scalability.

Why Migrate to .NET Core? (Key Benefits)

Faster Performance: .NET Core runs up to 30% faster than .NET Framework.
Cloud-Ready: Over 80% of enterprises prefer cloud-native apps, and .NET Core is built for modern cloud environments.
Future-Proof: Microsoft is ending support for .NET Framework, so .NET Core is the future of .NET development.

Cross-Platform: Run your application on Windows, Linux, and macOS without major changes.

Sparkle Web: Your Partner in .NET Core Migration!

Migrating a .NET Framework application to .NET Core is a complex task, but Sparkle Web can make it easy for you!

End-to-End Migration Services customized to your needs.
Performance Optimization to ensure smooth and fast-running applications.
Cloud & Containerization Support for future-ready applications.

Want to migrate your .NET Framework app to .NET Core? Let’s Talk!

Conclusion

Migrating to .NET Core unlocks better performance, stronger security, and cross-platform flexibility. With the right approach, detailed planning, and expert guidance, you can make the transition without disrupting your business operations.

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6 Steps to Migrate your .NET Framework App to .NET Core