Upgrade C# code to use newer C# language features. Use this skill whenever the user wants to modernize C# code to a specific language version (e.g., "upgrade to C# 12", "use latest C# features", "modernize this C# code"), apply new language features from any C# version 7.0 through 15, or when migrating a .NET project to a newer target framework and the C# language version increases.
Install
npx skills add microsoft/upgrade-agent-plugins --skill modernizing-csharp-versionnpx skills add microsoft/upgrade-agent-plugins --skill modernizing-csharp-version -a claude-code -gnpx skills add microsoft/upgrade-agent-plugins --skill modernizing-csharp-version -a codex -ggemini skills install https://github.com/microsoft/upgrade-agent-plugins.git --path plugins/upgrade-agent/upgrade/dotnet/skills/lazy/common/modernizing-csharp-versiongh skill install microsoft/upgrade-agent-plugins modernizing-csharp-versiongit clone --depth 1 https://github.com/microsoft/upgrade-agent-plugins /tmp/microsoft__upgrade-agent-plugins
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/microsoft__upgrade-agent-plugins/plugins/upgrade-agent/upgrade/dotnet/skills/lazy/common/modernizing-csharp-version ~/.claude/skills/modernizing-csharp-version # Claude Code
cp -R /tmp/microsoft__upgrade-agent-plugins/plugins/upgrade-agent/upgrade/dotnet/skills/lazy/common/modernizing-csharp-version ~/.agents/skills/modernizing-csharp-version # Codex, Cursor, Gemini CLI, Copilot, OpenCode