How to Migrate from .NET Framework to .NET 10: A Step-by-Step Guide

If your business still runs important applications on .NET Framework 4.x, you are in good company. Thousands of companies depend on ASP.NET MVC portals, Web Forms admin panels, WCF services and Windows desktop tools built more than a decade ago. They still work, but they are falling behind. .NET Framework now receives security and reliability fixes only, while every new feature, performance gain and tooling improvement goes into modern .NET.

That is why so many teams are planning to migrate .NET Framework to .NET 10 this year. .NET 10 is a Long-Term Support (LTS) release, it runs on Windows, Linux and containers, and it is far faster than the framework most legacy apps were built on.

In this .NET 10 upgrade guide, we walk through the full process: why to migrate, how to assess your application, which tools to use, the step-by-step migration itself, ASP.NET MVC and Entity Framework specifics, testing, deployment, and the common problems teams hit along the way. It is written for CTOs, development leads and business owners who want a clear, practical plan.

Why Migrate from .NET Framework to .NET 10 in 2026?

1. Better performance and scalability

Modern .NET has been rebuilt for speed. Faster startup, lower memory use and higher request throughput mean the same application can serve more users on less hardware. For high-traffic web apps and APIs, that difference shows up directly in hosting bills and user experience.

2. Long-term support

.NET 10 is an LTS release, which means Microsoft supports it with patches for three years from its November 2025 launch. You can check the current dates on the official .NET support policy page. Moving to an LTS version gives you a stable platform to build on instead of a framework that is effectively frozen.

3. Cross-platform, cloud and container deployment

.NET Framework ties you to Windows Server and IIS whereas .NET 10 runs on Linux, inside Docker containers, on Azure App Service, Azure Container Apps, AWS and Kubernetes. That freedom opens the door to cheaper hosting and modern DevOps practices.

4. Lower infrastructure costs

Linux hosting and container density usually cost less than dedicated Windows servers. Many businesses find that the savings on infrastructure help pay for the migration itself over time.

5. Security and hiring

Modern .NET receives the newest security features, and today’s developers are trained on it. Keeping a legacy stack alive makes it harder to hire and retain good engineers.

.NET Framework vs .NET 10: Key Differences

Before you start, it helps to understand that this is not a simple version bump. Moving to .NET 10 is an architectural shift, which is why many companies treat it as a legacy .NET modernization project rather than a routine upgrade.

Before You Start: Assess Your Application

A good assessment saves weeks later. Spend time here before you change a single line of code.

Inventory your projects and dependencies

List every project in the solution, its type (web, class library, Windows service, desktop), and every NuGet package and third-party DLL it uses. For each dependency, check whether a .NET 10-compatible version exists. Libraries that target .NET Standard 2.0 will usually work on both old and new runtimes.

Identify technologies that do not exist in modern .NET

Some .NET Framework technologies were never brought forward. Flag these early because they need redesign, not just recompiling:

• ASP.NET Web Forms needs to be rewritten as Razor Pages, MVC or Blazor.
• WCF server-side services can move to CoreWCF, gRPC or REST APIs.
• AppDomains, .NET Remoting and Code Access Security need alternative designs.
• System.Web dependencies such as HttpContext.Current must be refactored.

Choose your approach: rewrite or incremental

For small apps, a direct port in one go is often fine. For large, business-critical systems, an incremental migration is safer. You run the old and new apps side by side behind a reverse proxy and move features across one route at a time, so users never face a risky “big bang” cutover.

Estimate effort and risk

Score each project by size, test coverage, and how many unsupported technologies it uses. This gives you a realistic timeline and helps you decide what to migrate first.

Tools That Make the Migration Easier

• .NET Upgrade Assistant and GitHub Copilot app modernization: The .NET Upgrade Assistant analyses your solution, converts project files and updates target frameworks and packages. Microsoft is now steering teams towards its AI-assisted GitHub Copilot app modernization tooling, which covers similar ground.
• SDK-style project conversion: Modern .NET uses short, clean .csproj files. Converting to this format is the first practical step.
• API compatibility analyzers: Built-in analyzers flag APIs that are missing or behave differently on .NET 10.
• System.Web adapters and YARP: Microsoft’s System.Web adapters and the YARP reverse proxy let old and new apps share sessions and traffic during an incremental migration.

Microsoft’s official porting guide is a useful reference alongside these tools.

Step-by-Step: .NET Framework 4.8 to .NET 10 Migration

Most legacy business apps run on .NET Framework 4.8, so this section focuses on that path. Here is the approach that we follow for client’s projects.

Step 1: Convert projects to SDK-style format

Replace the old, verbose project file with an SDK-style file and set the target framework to net10.0.

<Project Sdk=”Microsoft.NET.Sdk.Web”>

  <PropertyGroup>

    <TargetFramework>net10.0</TargetFramework>

    <Nullable>enable</Nullable>

    <ImplicitUsings>enable</ImplicitUsings>

  </PropertyGroup>

</Project>

Step 2: Move shared libraries to .NET Standard 2.0 or multi-target

Start with class libraries that hold business logic. Target .NET Standard 2.0, or multi-target both runtimes, so the old app and the new app can use the same code during the transition.

<TargetFrameworks>net48;net10.0</TargetFrameworks>

Step 3: Update NuGet packages and replace incompatible libraries

Upgrade every package to a version that supports .NET 10. Replace packages that have no modern version with maintained alternatives. Common swaps include System.Web.Mvc to Microsoft.AspNetCore.Mvc and EntityFramework to Microsoft.EntityFrameworkCore.

Step 4: Migrate configuration

Move settings out of Web.config into appsettings.json and read them through IConfiguration or the strongly typed Options pattern.

// appsettings.json

{

  “ConnectionStrings”: { “Default”: “Server=.;Database=AppDb;Trusted_Connection=True;” },

  “AppSettings”: { “SupportEmail”: “support@example.com” }

}

// Reading a value

var email = builder.Configuration[“AppSettings:SupportEmail”];

Step 5: Replace Global.asax and HttpModules with Program.cs and middleware

This is the biggest conceptual change. Application start-up logic moves into Program.cs, and HttpModules become middleware in the request pipeline.

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddControllersWithViews();

var app = builder.Build();

app.UseStaticFiles();

app.UseRouting();

app.UseAuthentication();

app.UseAuthorization();

app.MapControllerRoute(“default”, “{controller=Home}/{action=Index}/{id?}”);

app.Run();

Step 6: Set up dependency injection and logging

Register your services with the built-in container instead of a third-party one, and switch to the built-in ILogger abstraction. This makes the code easier to test and maintain.

Step 7: Migrate authentication

ASP.NET Membership and older OWIN setups are replaced by ASP.NET Core Identity, cookie authentication, or an external provider such as Microsoft Entra ID. Plan a password-hash migration strategy so existing users can still sign in.

ASP.NET MVC to .NET 10 Migration: What Changes

ASP.NET MVC 5 apps are the most common type we see, and they map fairly cleanly to ASP.NET Core MVC. Here is what changes during an ASP.NET MVC to .NET 10 migration, and where teams usually spend their time. If you would rather hand this part to specialists, our ASP.NET MVC to .NET 10 migration services cover it end to end.

Controllers and routing

Controllers move from System.Web.Mvc to Microsoft.AspNetCore.Mvc. ActionResult types are similar, but filters, model binding and routing are configured differently. Attribute routing works in much the same way.

Razor views, HTML helpers and Tag Helpers

Most Razor views carry over with small edits. Many HTML helpers still work, but Tag Helpers are cleaner and easier for front-end developers to read. Child actions are replaced by View Components.

Bundling and minification

System.Web.Optimization (@Scripts.Render and @Styles.Render) does not exist in ASP.NET Core. Replace it with a build-time tool such as WebOptimizer, Vite or a simple npm build step.

What about Web Forms?

Web Forms has no direct equivalent in .NET 10, so pages must be rebuilt. Razor Pages suit simple, page-based apps, while Blazor is a good fit if your team likes component-based UI with C#. This is usually the most time-consuming part of any migration.

Running a complex ASP.NET MVC or Web Forms application? Talk to our .NET migration team for a free assessment and a realistic migration plan.

EF6 to EF Core Migration

Data access is the other big piece. An EF6 to EF Core migration is usually straightforward for code-first models, but there are differences you need to plan for:

• EDMX models are not supported. Reverse-engineer the database into code-first classes with the scaffolding tools.
• Lazy loading is off by default. Enable it with proxies, or better, use explicit Include() calls.
• Query behaviour differs in some edge cases, so test complex LINQ queries carefully.
• Performance is a major win: EF Core is noticeably faster for most workloads.

Microsoft’s EF6 to EF Core porting guide lists the detailed differences.

Testing and Validating Your Migrated Application

A migration is only successful if the new app behaves exactly like the old one. Build confidence with:

• Unit and integration tests around business rules before you start, so you can prove nothing has changed.
• Regression testing of key user journeys such as login, checkout, reporting and admin tasks.
• Performance benchmarks comparing response times and memory use before and after.
• Side-by-side runs where both versions process the same requests and you compare results.

Deploying Your .NET 10 Application

.NET 10 gives you more deployment options than you had before:

• IIS on Windows Server using the ASP.NET Core Hosting Bundle, if you want to keep your current servers.
• Linux servers behind Nginx or Apache for lower hosting costs.
• Docker containers on Kubernetes, Azure Container Apps or AWS ECS.
• Azure App Service for a fully managed option.

For incremental migrations, put a YARP reverse proxy in front of both apps and switch routes to the new version one at a time.

Common Migration Challenges and How to Solve Them

How Long Does a .NET Framework to .NET 10 Migration Take?

Every project is different, but as a rough guide:

• Small apps (a single web app or API, good test coverage): a few weeks.
• Medium apps (several projects, MVC with some WCF): two to four months.
• Large enterprise systems (Web Forms, many integrations, little test coverage): six months or more, usually done incrementally.

The biggest factors are the amount of Web Forms and WCF code, the state of your test suite, and how many third-party libraries need replacing.

Frequently Asked Questions

Can I migrate directly from .NET Framework 4.8 to .NET 10?

Yes. You do not need to pass through .NET Core 3.1, .NET 6 or .NET 8 first. You can target net10.0 directly, as long as your dependencies support it.

Should I choose .NET 8 or .NET 10?

For new migration projects in 2026, .NET 10 is the better choice. Both are LTS releases, but .NET 10 is supported for longer and includes the latest performance improvements.

Can .NET Framework and .NET 10 run on the same server?

Yes. They install side by side, and IIS can host both using separate application pools. This makes incremental migration much easier.

Is .NET Framework 4.8 being discontinued?

.NET Framework 4.8.1 is still supported as part of supported Windows versions, but it only receives security and reliability fixes. No new features are being added.

How much does a .NET migration cost?

Cost depends on the size of the codebase, the technologies involved and the level of testing required. The best way to get an accurate figure is a code assessment, which we offer free of charge.

Conclusion: Start Your .NET 10 Migration with a Clear Plan

Choosing to migrate .NET Framework to .NET 10 is one of the best long-term investments you can make in your software. You gain speed, lower hosting costs, cloud and container options, and a platform that will keep improving for years. The key is to plan carefully: assess your application, pick the right tools, migrate in safe steps, and test thoroughly.

At Softwiz Infotech, we specialise in legacy .NET maintenance and modernisation for businesses across the UK, United States, Dubai, Australia and Europe. Whether you have a single MVC app or a large Web Forms and WCF system, our team can take it to .NET 10 with minimal disruption to your users.

Ready to modernise? Book a free .NET migration assessment and get a clear plan, timeline and cost estimate for your application.