---
title: ".NET Modernization with Autohand Code"
source: https://docs.autohand.ai/guides/dotnet-modernization
---

# .NET Modernization with Autohand Code

Upgrade legacy .NET Framework applications to modern .NET 8+. Transform ASP.NET applications and modernize your .NET stack with Autohand Code.

**.NET 8 Benefits:** Modern .NET offers significant performance improvements, better cloud integration, and enhanced security. Autohand Code helps teams migrate 500K+ lines of .NET Framework code with 99.5% accuracy. [Read the case study](/updates/modernizing-legacy-dotnet-applications).

**Related Skills:** Accelerate your .NET modernization with specialized skills from [Skilled](https://skilled.autohand.ai). Browse [ASP.NET Core migration skills](https://skilled.autohand.ai/categories/frameworks), [C# modernization skills](https://skilled.autohand.ai/categories/languages), and [containerization skills](https://skilled.autohand.ai/categories/cloud) for your migration journey.

## Why modernize .NET?

Modern .NET offers compelling advantages over .NET Framework:

-   Cross-platform deployment (Linux, macOS, Windows)
-   Container and cloud-native support
-   Significant performance improvements (2-3x faster)
-   Smaller deployment footprints
-   Modern C# features and language improvements
-   Long-term support and regular updates

## .NET codebase analysis

Evaluate your .NET Framework application for migration readiness:

``` bash
# Analyze .NET Framework codebase
autohand analyze --framework dotnet --version 4.8 \
  --target-version 8.0 \
  --output dotnet-analysis.json

# Analysis includes:
# - Framework compatibility issues
# - Third-party library support
# - Windows-specific dependencies
# - Migration complexity assessment
```

## .NET Framework to .NET 8 migration

Automatically migrate from .NET Framework to modern .NET:

``` bash
# Migrate to .NET 8
autohand migrate-dotnet --from framework --to 8.0 \
  --target-platform linux \
  --container-support

# Key transformations:
# - Project file format conversion
# - Package reference updates
# - API compatibility fixes
# - Configuration modernization
```

### Project file transformation

``` xml

<Project ToolsVersion="15.0" DefaultTargets="Build">
  <PropertyGroup>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    <Platform Condition=" '$(Platform)' == '' ">x86</Platform>
    <TargetFrameworkVersion>v4.8</TargetFrameworkVersion>
  </PropertyGroup>
  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
</Project>
```

Becomes:

``` xml

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>
</Project>
```

## ASP.NET to ASP.NET Core migration

Transform legacy ASP.NET applications to modern ASP.NET Core:

``` bash
# Migrate ASP.NET Web Forms/MVC
autohand migrate-aspnet --from webforms --to core \
  --target-version 8.0 \
  --razor-pages

# Migrate Web API
autohand migrate-aspnet --from webapi --to core \
  --minimal-apis \
  --swagger-integration
```

### Controller transformation example

``` csharp
// Before (ASP.NET MVC 5)
public class ProductsController : Controller
{
    private readonly ProductService _service;
    
    public ProductsController()
    {
        _service = new ProductService();
    }
    
    [HttpGet]
    public ActionResult Index()
    {
        var products = _service.GetAll();
        return View(products);
    }
    
    [HttpPost]
    public ActionResult Create(Product product)
    {
        if (ModelState.IsValid)
        {
            _service.Create(product);
            return RedirectToAction("Index");
        }
        return View(product);
    }
}
```

Becomes:

``` csharp
// After (ASP.NET Core 8)
public class ProductsController : ControllerBase
{
    private readonly ProductService _service;
    
    public ProductsController(ProductService service)
    {
        _service = service;
    }
    
    [HttpGet]
    public async Task<ActionResult<IEnumerable<Product>>> GetAll()
    {
        var products = await _service.GetAllAsync();
        return Ok(products);
    }
    
    [HttpPost]
    public async Task<ActionResult<Product>> Create(Product product)
    {
        await _service.CreateAsync(product);
        return CreatedAtAction(nameof(GetById), new { id = product.Id }, product);
    }
}
```

## Dependency injection modernization

Convert to modern dependency injection patterns:

``` csharp
// Before (manual DI or custom containers)
public class OrderService
{
    private readonly IOrderRepository _repository;
    private readonly IEmailService _emailService;
    
    public OrderService()
    {
        _repository = new OrderRepository();
        _emailService = new EmailService();
    }
}
```

Becomes:

``` csharp
// After (built-in DI)
public class OrderService
{
    private readonly IOrderRepository _repository;
    private readonly IEmailService _emailService;
    
    public OrderService(IOrderRepository repository, IEmailService emailService)
    {
        _repository = repository;
        _emailService = emailService;
    }
}

// Program.cs registration
builder.Services.AddScoped<IOrderRepository, OrderRepository>();
builder.Services.AddScoped<IEmailService, EmailService>();
builder.Services.AddScoped<OrderService>();
```

## Configuration modernization

Migrate from web.config to modern configuration:

``` xml

<configuration>
  <appSettings>
    <add key="ConnectionString" value="Server=...;Database=..." />
    <add key="ApiKey" value="..." />
  </appSettings>
  <connectionStrings>
    <add name="DefaultConnection" connectionString="..." />
  </connectionStrings>
</configuration>
```

Becomes:

``` json
// After (appsettings.json)
{
  "ConnectionStrings": {
    "DefaultConnection": "Server=...;Database=..."
  },
  "AppSettings": {
    "ApiKey": "..."
  }
}

// Program.cs
var connectionString = builder.Configuration.GetConnectionString("DefaultConnection");
var apiKey = builder.Configuration["AppSettings:ApiKey"];
```

## Testing and validation

Ensure migration doesn't break functionality:

``` bash
# Generate migration tests
autohand generate-tests --framework dotnet \
  --target-version 8.0 \
  --test-framework xunit

# Run migration validation
autohand validate-migration --from framework --to 8.0 \
  --run-tests \
  --performance-benchmark

# Compare behavior
autohand compare --before framework-output \
  --after dotnet8-output \
  --tolerance 0.01
```

## Container deployment

Containerize modernized .NET applications:

``` bash
# Generate Docker files
autohand containerize --framework dotnet --target 8.0 \
  --base-image mcr.microsoft.com/dotnet/aspnet:8.0 \
  --runtime-alpine

# Generate Kubernetes manifests
autohand generate-k8s --framework dotnet \
  --service-type webapi \
  --ingress-enabled
```

### Example Dockerfile

``` dockerfile
# Generated Dockerfile
FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
WORKDIR /src
COPY ["MyApp.csproj", "./"]
RUN dotnet restore "MyApp.csproj"
COPY . .
RUN dotnet publish "MyApp.csproj" -c Release -o /app/publish

FROM mcr.microsoft.com/dotnet/aspnet:8.0 AS final
WORKDIR /app
COPY --from=build /app/publish .
ENTRYPOINT ["dotnet", "MyApp.dll"]
```

## Best practices for .NET modernization

-   Start with stateless services and utilities
-   Maintain comprehensive test coverage
-   Use feature flags for gradual rollout
-   Monitor performance metrics post-migration
-   Leverage container orchestration for deployment
-   Plan for Windows-specific dependencies

## Success story: Enterprise ERP system

A manufacturing company migrated their ERP system:

-   **Scope:** 1.8M lines of .NET Framework 4.8 code
-   **Target:** .NET 8 + ASP.NET Core + Linux containers
-   **Timeline:** 15 months phased migration
-   **Results:** 3x performance improvement, 70% cost reduction
-   **Deployment:** Kubernetes on Azure with auto-scaling