Migrating a project from .NET 6 or .NET 7 to .NET 8 involves updating SDK versions, ensuring compatibility of dependencies, and making minimal code changes due to .NET’s strong focus on backward compatibility.

Step-by-Step Guide on Migration from .NET 7 to .NET 8

Step 1: Install .NET 8 SDK

  1. Download from .NET 8
  2. After installation, verify:
dotnet --list-sdks

Step 2: Update TargetFramework in Project Files

Example .csproj changes:

From:

<TargetFramework>net7.0</TargetFramework>

To:

<TargetFramework>net8.0</TargetFramework>

If it’s a multi-targeted project:

<TargetFrameworks>net8.0;net7.0</TargetFrameworks>

Step 3: Update NuGet Packages

  1. In Visual Studio: Right-click on the solution > Manage NuGet Packages > Update tab.
  2. Or via CLI:
dotnet list package --outdated
dotnet add package [PackageName] --version [LatestVersion]

Note:

Some packages might have breaking changes in .NET 8 or may not yet support it — check release notes and alternatives.

Step 4: Update Global.json (If used)

If your project uses a global.json to pin the SDK version:

Before:

{ "sdk": { "version": "7.0.100" }
}

After:

{ "sdk": { "version": "8.0.100" }
}

Step 5: Check for Deprecated APIs or Warnings

Build your solution:

dotnet build

Check for build warnings or deprecated APIs.

.NET 8 may introduce new analyzers or behaviors (especially in ASP.NET Core or EF Core), so fix any warnings or errors during the build.

Step 6: Test the Application

  1. Run all unit/integration tests.
  2. Verify third-party packages (e.g., Swashbuckle, AutoMapper, MediatR).
  3. Validate key functionality in local, staging, and production environments.

Step 7: Optional Code Modernization

After confirming compatibility, you can leverage new features in .NET 8, such as:

  • Primary Constructors in classes
  • Performance improvements
  • New APIs in collections, spans, etc.
  • Blazor Web App hybrid rendering
  • ASP.NET Core improvements like route tooling, endpoint filters

Example: Migrating a Minimal API from .NET 7 to .NET 8

Before (.NET 7)

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();
app.MapGet("/", () => "Hello from .NET 7!");
app.Run();

After (.NET 8) Just update the SDK and TargetFramework. The code doesn’t change unless you want to leverage .NET 8 features.

<!-- Updated .csproj --><TargetFramework>net8.0</TargetFramework>

Optional enhancement in .NET 8:

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();
app.MapGet("/", () => TypedResults.Ok("Hello from .NET 8!"));
app.Run();

Final Thoughts

  • .NET 8 is an LTS version (Long-Term Support), making it a good target for production workloads.
  • Migration is mostly straightforward with minimal code refactor if you stick with compatible libraries.