dotnet-sdk-style-upgrade

name	dotnet-sdk-style-upgrade
description	**WORKFLOW SKILL** — Convert legacy .NET project files (.csproj, .fsproj, .vbproj) to modern SDK-style format. WHEN: "modernize .NET project", "upgrade csproj to SDK-style", "migrate to SDK-style project", "convert legacy .NET project", "non-SDK-style project upgrade". INVOKES: file system tools for project file analysis. FOR SINGLE OPERATIONS: Edit the project file XML directly.
metadata	{"author":"microsoft-foundry-jumpstart","version":"1.0","reference":"https://learn.microsoft.com/en-us/dotnet/core/project-sdk/overview"}

Upgrading to SDK-Style Projects

Required Reference: Before proceeding, consult the .NET SDK-style project documentation for authoritative guidance on SDK-style projects.

SDK Selection Guide

Analyze project files to recommend the appropriate SDK:

Project Type	SDK	Indicators
Console/Library	Microsoft.NET.Sdk	No web/UI references
ASP.NET Core/Web API	Microsoft.NET.Sdk.Web	Microsoft.AspNetCore.*, Startup.cs, Controllers
Razor Class Library	Microsoft.NET.Sdk.Razor	.razor files, Razor components
Blazor WebAssembly	Microsoft.NET.Sdk.BlazorWebAssembly	Microsoft.AspNetCore.Components.WebAssembly
Worker/Background Service	Microsoft.NET.Sdk.Worker	IHostedService, BackgroundService
WinForms	Microsoft.NET.Sdk + <UseWindowsForms>	System.Windows.Forms
WPF	Microsoft.NET.Sdk + <UseWPF>	PresentationFramework, .xaml files
MSTest	MSTest.Sdk	Microsoft.VisualStudio.TestTools.UnitTesting
.NET Aspire AppHost	Aspire.AppHost.Sdk	Aspire orchestration project

Analysis Checklist

Before upgrading, analyze and review:

• Project type: Console, library, web, test, desktop, or worker
• Target framework: Current TFM and desired target (e.g., net9.0, net48)
• Package references: Check packages.config or <Reference> with HintPath
• Assembly references: GAC or local assemblies that need conversion
• Conditional compilation: #if directives, DEBUG/RELEASE configurations
• Build configurations: Custom configurations beyond Debug/Release
• Pre/Post build events: Scripts in <PreBuildEvent> or <PostBuildEvent>
• Custom targets/props: .targets or .props file imports
• AssemblyInfo.cs: Attributes to migrate or auto-generate
• Resources: .resx files, embedded resources, content files
• Project references: Other projects in solution
• COM references: ActiveX/COM interop dependencies
• WCF/ASMX references: Service references requiring migration
• Project GUIDs: Solution file references (update if changing)
• Output paths: Custom OutputPath, IntermediateOutputPath
• Signing: Strong name keys, delay signing settings
• Platform target: x86, x64, AnyCPU, ARM settings

Upgrade Process

1. Identify SDK: Analyze references and file patterns to determine SDK

2. Create minimal project file:

   <Project Sdk="SELECTED_SDK">
     <PropertyGroup>
       <TargetFramework>net9.0</TargetFramework>
       <Nullable>enable</Nullable>
       <ImplicitUsings>enable</ImplicitUsings>
     </PropertyGroup>
   </Project>
   

3. Add OutputType if executable: <OutputType>Exe</OutputType> or <OutputType>WinExe</OutputType>

4. Migrate PackageReferences: Convert packages.config or HintPath references

5. Remove redundant elements: SDK-style auto-includes *.cs, *.resx, etc.

6. Add desktop properties for WinForms/WPF:

   <UseWindowsForms>true</UseWindowsForms>
   <!-- or -->
   <UseWPF>true</UseWPF>
   

Key Differences from Legacy

• No <Compile Include="**/*.cs" /> needed (auto-included)
• No assembly info file needed (<GenerateAssemblyInfo>true</GenerateAssemblyInfo> default)
• PackageReference replaces packages.config
• No ProjectGuid, ProjectTypeGuids required
• No explicit SDK imports needed

Validation

After upgrade, run:

dotnet build
dotnet msbuild -preprocess:output.xml  # View expanded project