Migrate Nullable References
Enable nullable reference types in a C# project and systematically resolve all warnings.
Install
npx skills add managedcode/dotnet-skills --skill migrate-nullable-references -g -a claude-code -y- Repository
- managedcode/dotnet-skills500
- Category
- Engineering
- Updated
- 6d ago
- License
- MIT
- Context cost
- Mediumabout 3,000 tokens
- Runs scripts
- No, instructions only
What it does
Enable nullable reference types in a C# project and systematically resolve all warnings. USE FOR: adopting NRTs in existing codebases, file-by-file or project-wide migration, fixing CS8602/CS8618/CS86xx warnings, annotating APIs for nullability, cleaning up null-forgiving operators, upgrading dependencies with new nullable annotations. DO NOT USE FOR: projects already fully migrated with zero warnings (unless auditing suppressions), fixing a handful of nullable warnings in code that already has NRTs enabled, suppressing warnings without fixing them, C# 7.3 or earlier projects. INVOKES: Get-NullableReadiness.ps1 scanner script.
Nullable Reference Migration
Enable C# nullable reference types (NRTs) in an existing codebase and systematically resolve all warnings. The outcome is a project (or solution) with <Nullable>enable</Nullable>, zero nullable warnings, and accurately annotated public API surfaces, giving both the compiler and consumers reliable nullability information.
When to Use
- Enabling nullable reference types in an existing C# project or solution
- Systematically resolving CS86xx nullable warnings after enabling the feature
- Annotating a library's public API surface so consumers get accurate nullability information
- Upgrading a dependency that has added nullable annotations and new warnings appear
- Analyzing suppressions in a code base that has already enabled NRTs to determine whether they can be removed
When Not to Use
- The project already has
<Nullable>enable</Nullable>and zero warnings, the migration is done unless the user wants to re-examine suppressions with a view to removing unnecessary ones (see Step 6) - The user only wants to suppress warnings without fixing them (recommend against this)
- The code targets C# 7.3 or earlier, which does not support nullable reference types
Inputs
| Input | Required | Description |
|---|---|---|
| Project or solution path | Yes | The .csproj, .sln, or build entry point to migrate |
| Migration scope | No | project-wide (default) or file-by-file, controls the rollout strategy |
| Build command | No | How to build the project (e.g., dotnet build, msbuild, or a repo-specific build script). Detect from the repo if not provided |
| Test command | No | How to run tests (e.g., dotnet test, or a repo-specific test script). Detect from the repo if not provided |
