Migrating from .NET Framework to .NET 10: Common Challenges and Solutions

Introduction

Many organizations still run business-critical applications on the .NET Framework. These applications have been reliable for years, but modern development requirements such as cross-platform support, better performance, cloud deployment, and long-term support have encouraged many teams to migrate to the latest .NET platform.

Migrating from .NET Framework to .NET 10 is not simply changing the target framework in your project file. It requires careful planning, testing, and sometimes redesigning parts of your application. The good news is that most migrations can be completed gradually with the right approach.

In this article, we'll explore the most common migration challenges, practical solutions, and best practices to help make your migration smoother.

Why Migrate to .NET 10?

The modern .NET platform offers several advantages over the traditional .NET Framework.

Some of the key benefits include:

• Better application performance

• Cross-platform development for Windows, Linux, and macOS

• Improved security and long-term support

• Faster startup times

• Lower memory usage

• Better cloud and container support

• Continuous feature updates

These improvements make .NET 10 a strong choice for both new and existing applications.

Assess Your Existing Application

Before starting the migration, understand your application's current architecture.

Review the following:

• Project types

• Third-party libraries

• Database dependencies

• Windows-specific APIs

• Configuration files

• Authentication methods

• Background services

This assessment helps identify components that may require additional work during migration.

Challenge 1: Unsupported APIs

One of the biggest migration challenges is that some APIs available in the .NET Framework are not available in modern .NET.

For example, older applications may depend on Windows-only technologies such as:

• Web Forms

• .NET Remoting

• AppDomains

• WCF Server

• System.Drawing in server environments

Solution

Replace unsupported technologies with modern alternatives.

For example:

Migrating gradually reduces project risk.

Challenge 2: NuGet Package Compatibility

Older projects often depend on packages that were built only for the .NET Framework.

For example:

<PackageReference Include="LegacyLibrary" Version="2.0.0" />

After migration, the package may fail to compile because it doesn't support .NET 10.

Solution

Check whether newer package versions support modern .NET.

If a package is no longer maintained:

• Find a supported alternative.

• Replace custom implementations where necessary.

• Remove unused dependencies.

Always test the replacement thoroughly before deployment.

Challenge 3: Project File Conversion

Older applications typically use the traditional project format.

Modern .NET uses a much simpler SDK-style project.

Old format:

<Project ToolsVersion="15.0">

Modern format:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
  </PropertyGroup>

</Project>

The new format is cleaner, easier to maintain, and reduces unnecessary configuration.

Challenge 4: Configuration Changes

The .NET Framework commonly stores settings inside Web.config or App.config.

Modern .NET uses appsettings.json.

Example:

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=.;Database=DemoDb;Trusted_Connection=True;"
  }
}

Configuration values can also come from:

• Environment variables

• Azure Key Vault

• User Secrets

• Command-line arguments

This approach makes applications more flexible and cloud-friendly.

Challenge 5: Dependency Injection

Many .NET Framework applications manually create objects.

Example:

var service = new ProductService();

Modern .NET includes built-in Dependency Injection (DI).

Register services:

builder.Services.AddScoped<IProductService, ProductService>();

Use constructor injection:

public class ProductController
{
    private readonly IProductService _service;

    public ProductController(IProductService service)
    {
        _service = service;
    }
}

Dependency Injection improves testability, maintainability, and code organization.

Challenge 6: Authentication and Security

Older applications often use Forms Authentication or Windows Authentication with legacy configuration.

Modern .NET supports more flexible authentication options, including:

• Microsoft Entra ID

• JWT Bearer Tokens

• OAuth 2.0

• OpenID Connect

• Cookie Authentication

If you're modernizing an application, this is a good opportunity to improve your authentication and authorization strategy.

Challenge 7: Testing After Migration

Even if the application compiles successfully, the migration isn't complete until it's fully tested.

Focus on:

• Functional testing

• API testing

• Performance testing

• Database validation

• Authentication testing

• Integration testing

• User acceptance testing

Testing helps identify behavioral differences that may not appear during compilation.

Practical Migration Strategy

Instead of migrating everything at once, use a phased approach.

1. Analyze the existing application.

2. Upgrade NuGet packages.

3. Convert projects to SDK style.

4. Migrate one project or module at a time.

5. Replace unsupported APIs.

6. Perform automated and manual testing.

7. Deploy gradually and monitor application health.

This strategy reduces downtime and minimizes migration risks.

Best Practices

Follow these recommendations for a successful migration:

• Start with smaller projects before migrating large enterprise applications.

• Keep the original application available until the migration is complete.

• Update all NuGet packages before beginning the migration.

• Replace unsupported APIs early in the process.

• Use built-in Dependency Injection instead of manual object creation.

• Move configuration settings to appsettings.json.

• Automate testing wherever possible.

• Monitor performance after deployment to identify optimization opportunities.

• Review Microsoft's migration documentation for platform-specific guidance.

Conclusion

Migrating from the .NET Framework to .NET 10 is an investment that brings long-term benefits, including better performance, improved security, cross-platform support, and easier cloud deployment. While challenges such as unsupported APIs, outdated packages, configuration changes, and dependency management are common, they can be addressed with proper planning and a phased migration strategy.

Rather than treating migration as a one-time task, view it as an opportunity to modernize your application's architecture, simplify maintenance, and prepare your software for future growth. With careful testing and gradual implementation, organizations can successfully transition to .NET 10 while minimizing risk and disruption.