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migrate-dotnet8-to-dotnet9

Migrate .NET 8 projects to .NET 9 by updating TargetFramework and dependencies.

2|Updated Mar 17, 2026
Search Tags:#migration#dotnet#upgrade#net9#ef-core#aspnet-core#build-errors
One-click install
npx skills add https://github.com/sayedihashimi/copilot-skill-eval --skill migrate-dotnet8-to-dotnet9-sayedihashimi
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: migrate-dotnet8-to-dotnet9
Source: https://github.com/sayedihashimi/copilot-skill-eval/tree/main/examples/aspnet-razor-pages/plugins/dotnet-skills/dotnet-upgrade/skills/migrate-dotnet8-to-dotnet9
Command: npx skills add https://github.com/sayedihashimi/copilot-skill-eval --skill migrate-dotnet8-to-dotnet9-sayedihashimi

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Migrate a .NET 8 project to .NET 9 and resolve breaking changes to deliver a net9.0 target with compatible code and behavior.

Core Features & Use Cases

  • Upgrade TargetFramework to net9.0 and align dependencies across ASP.NET Core, EF Core, and related libraries.
  • Detect and resolve breaking changes introduced in .NET 9, including compiler, runtime, and API surface updates.
  • Use case: Upgrade a legacy .NET 8 web application to .NET 9 with minimal functional drift and clear migration steps.

Quick Start

Run the upgrade workflow on your .NET 8 project to target net9.0 and verify all build and runtime changes.

Frequently Asked Questions about migrate-dotnet8-to-dotnet9

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I migrate a .NET 8 project to .NET 9?▼

To migrate a .NET 8 project to .NET 9, the process updates the TargetFramework to net9.0 and aligns package references. This ensures ASP.NET Core and EF Core dependencies are compatible and resolves build errors for a clean dotnet restore.

What are common breaking changes when upgrading to .NET 9?▼

Upgrading to .NET 9 introduces breaking changes across compiler, runtime, and API surface updates. The migration process detects these changes and resolves them to deliver a net9.0 target with compatible code and minimal functional drift.

Does the .NET 9 migration process support ASP.NET Core and EF Core projects?▼

Yes, the .NET 9 migration process explicitly supports ASP.NET Core and EF Core projects. It aligns package references and related tooling to cover build, test, and runtime compatibility scenarios for your web applications.

What's the best way to resolve build errors after a .NET 9 upgrade?▼

The best way to resolve build errors after a .NET 9 upgrade is to align package references and apply the required migration steps. This ensures a clean dotnet restore/build and reports migration artifacts ready for review.

Can I upgrade a legacy .NET 8 web application to .NET 9 without functional drift?▼

You can upgrade a legacy .NET 8 web application to .NET 9 with minimal functional drift. The workflow detects and resolves breaking changes, ensuring runtime compatibility and clear migration steps for your project.

Why does my dotnet restore fail after upgrading the TargetFramework to net9.0?▼

Your dotnet restore fails after upgrading to net9.0 due to misaligned package references. The migration process addresses this by updating dependencies across ASP.NET Core and EF Core to ensure a clean build.

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