How to Upgrade to .NET 10 LTS - Complete Guide for .NET Global Tools with Multi-Targeting

Overview ☀

With .NET 10 now released as the latest Long-Term Support (LTS) version, it was time to upgrade SeedFolder to support the newest framework.

This comprehensive .NET 10 upgrade guide walks you through migrating a .NET global tool from .NET 8 and 9 to .NET 10 while maintaining full backward compatibility.

Whether you’re upgrading a .NET global tool, console application, or library, this migration tutorial covers everything you need: multi-target framework configuration, dependency management, CI/CD pipeline updates, and thorough testing strategies for a smooth .NET 10 migration.

Why Upgrade to .NET 10? 🎯

Migrating to .NET 10 LTS provides significant benefits for .NET developers. As the latest Long-Term Support release (supported until November 2028), upgrading to .NET 10 ensures your applications stay current with the latest framework improvements.

Benefits of upgrading to .NET 10:

• Latest LTS: Long-term support until November 2028
• Performance improvements: Built-in performance enhancements from .NET 10
• Forward compatibility: Automatic use of the highest installed SDK
• Backward compatibility: Continued support for .NET 8 (LTS) and .NET 9 (STS)

The beauty of multi-targeting during your .NET 10 migration is that users with any of these SDK versions can install and run the tool.

When multiple SDKs are installed, the .NET CLI automatically selects the highest compatible version, making your upgrade path seamless.

The Upgrade Process 🚀

The upgrade was surprisingly straightforward, thanks to .NET’s excellent multi-targeting support. Here’s the step-by-step process I followed:

1. Research and Planning 📚

Before making any changes, I researched the .NET 10 requirements:

• Target Framework Moniker (TFM): net10.0
• SDK Version: 10.0.100 or later
• Breaking Changes: Reviewed Microsoft docs for any breaking changes (none affecting SeedFolder)

I also reviewed the git history to understand how previous SDK upgrades were handled:

git log --all --grep=".NET" --oneline | head -20

This showed that the last major upgrade (PR #259c452) added .NET 8 and 9 support, following a similar pattern I could replicate.

2. Update Project File 🔧

The key change was adding net10.0 to the TargetFrameworks property in the .csproj file:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
-   <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
+   <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
    <LangVersion>latest</LangVersion>
    <ImplicitUsings>enable</ImplicitUsings>
    <PackAsTool>true</PackAsTool>
    <ToolCommandName>seedfolder</ToolCommandName>
    <PackageOutputPath>./nupkg</PackageOutputPath>
    <NoDefaultExcludes>true</NoDefaultExcludes>
-   <Version>1.3.3</Version>
+   <Version>1.4.0</Version>
    <!-- ... other properties ... -->
  </PropertyGroup>
</Project>

Important considerations:

• Use semicolon-separated list for multiple targets
• Bump the version number for NuGet release (1.3.3 → 1.4.0)
• Maintain existing targets for backward compatibility

3. Update CI/CD Pipeline ⚙️

The GitHub Actions workflow needed to install the .NET 10 SDK alongside existing versions:

- name: setup .net core sdk
  uses: actions/setup-dotnet@v4
  with:
      dotnet-version: |
        8.0.x
        9.0.x
+       10.0.x

This ensures the CI pipeline can build all three target frameworks.

4. Dependency Management 📦

I ran dotnet outdated to check for package updates:

dotnet tool install -g dotnet-outdated-tool
dotnet outdated

This revealed that Figgle (the ASCII art library) had a newer version (0.6.5). However, upon investigation, version 0.6.x introduced breaking changes by splitting fonts into a separate package. Since the upgrade goal was .NET 10 support, not dependency updates, I kept Figgle at 0.5.1 to avoid unnecessary complexity.

5. Build and Test ✅

Building for multiple frameworks is straightforward with multi-targeting:

dotnet build solrevdev.seedfolder.sln --configuration Release

Output showed successful builds for all three targets:

solrevdev.seedfolder -> src/bin/Release/net8.0/solrevdev.seedfolder.dll
solrevdev.seedfolder -> src/bin/Release/net9.0/solrevdev.seedfolder.dll
solrevdev.seedfolder -> src/bin/Release/net10.0/solrevdev.seedfolder.dll

Testing the Tool Locally 🧪

Before publishing, I packaged and tested the tool locally:

# Package the tool
dotnet pack -c Release -o /tmp/seedfolder-test

# Install from local package
dotnet tool uninstall -g solrevdev.seedfolder
dotnet tool install -g --add-source /tmp/seedfolder-test solrevdev.seedfolder

# Verify installation
seedfolder --version
# Output: seedfolder version 1.4.0

Then I tested various commands in /tmp to ensure functionality:

# Test dry-run mode
seedfolder --dry-run -t node test-node-app

# Create Python project
seedfolder -t python test-python-app

# Create .NET project
seedfolder --template dotnet test-dotnet-app

# Verify help and template listing
seedfolder --help
seedfolder --list-templates

All tests passed successfully! 🎉

6. Update Documentation 📝

Documentation updates included:

README.md - Updated requirements section:

## Requirements

- This tool requires **.NET 8.0 or .NET 9.0 SDK** to be installed
+ This tool requires **.NET 8.0, .NET 9.0, or .NET 10.0 SDK** to be installed

- **Runtime**: .NET 8.0 or later

CLAUDE.md - Updated framework information:

## Multi-Target Framework Support
- The project targets .NET 8.0 (LTS) and 9.0 (STS)
+ The project targets .NET 8.0 (LTS), 9.0 (STS), and 10.0 (LTS)
+ .NET 10 is the latest LTS release providing long-term support until November 2028.

Multi-Targeting Best Practices 💡

From this experience, here are some best practices for multi-targeting .NET global tools:

1. Use Multi-Targeting, Not Multiple Projects

<!-- Good: Single project, multiple targets -->
<TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>

<!-- Bad: Multiple projects for different versions -->

2. Maintain LTS Versions

Keep the previous LTS version (net8.0) alongside the new one. This gives users flexibility and ensures broad compatibility.

3. Test All Targets

The NuGet package includes all target frameworks:

tools/net8.0/any/solrevdev.seedfolder.dll
tools/net9.0/any/solrevdev.seedfolder.dll
tools/net10.0/any/solrevdev.seedfolder.dll

Verify each target builds correctly and the tool runs on all supported SDKs.

4. Handle Dependencies Carefully

When upgrading, check if dependencies support all your target frameworks. If a dependency doesn’t support your newest target, you have options:

• Keep the dependency at a compatible version
• Use conditional package references for different targets
• Find an alternative package

5. Update CI/CD First

Install all SDK versions in your CI pipeline before merging. This catches incompatibilities early:

- name: setup .net core sdk
  uses: actions/setup-dotnet@v4
  with:
      dotnet-version: |
        8.0.x
        9.0.x
        10.0.x

The Results 📊

After merging PR #17, the CI/CD pipeline automatically:

1. Built all three target frameworks
2. Ran integration tests
3. Packaged the NuGet package
4. Published version 1.4.0 to NuGet

Users can now install the updated version:

dotnet tool update --global solrevdev.seedfolder
seedfolder --version
# Output: seedfolder version 1.4.0

The tool automatically uses the highest installed SDK when run, so users with .NET 10 get the latest performance improvements while users on .NET 8 or 9 continue to work seamlessly.

Framework Support Timeline 📅

Current support timeline for SeedFolder:

Lessons Learned 🎓

1. Multi-targeting is powerful: Adding .NET 10 support while maintaining .NET 8 and 9 compatibility was trivial thanks to proper multi-targeting setup.

2. Dependency management matters: Always check dependencies when upgrading. Sometimes staying on older (but stable) dependency versions is the right choice.

3. Testing is essential: Local testing before publishing caught issues that automated tests might miss.

4. Documentation updates are important: Users need to know what versions are supported and what’s changed.

5. CI/CD automation pays off: Once configured properly, the entire build-test-publish pipeline runs automatically on merge.

What’s Next? 🔮

With .NET 10 support in place, SeedFolder is well-positioned for the future. The next areas of focus include:

• Template marketplace functionality (Issue #15)
• Additional project templates based on community feedback
• Enhanced template customization options

The full source code and history of this upgrade are available on GitHub.

Installation 📦

Try the latest version with .NET 10 support:

# Install or update to the latest version
dotnet tool update --global solrevdev.seedfolder

# Create a new project with your favorite template
seedfolder --template python my-new-project

# Or use interactive mode
seedfolder

Success! 🎉