How do I install the Dotnet 8 to 9 skill?

Run npx skillmds@latest add lawless-m/dotnet-8-to-9 in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is Dotnet 8 to 9 free to use?

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Who published Dotnet 8 to 9?

lawless-m (@lawless-m) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Dotnet 8 to 9 by lawless-m — Agent Skill

Name: Dotnet 8 to 9
Rating: 4.666666666666667 (3 reviews)
Author: lawless-m

File contents

.NET 8 → 9 Migration

Two modes — pick by what SDK is available:

Mode A: Pre-migration prep (still on .NET 8)

Use this in environments without the .NET 9 SDK. All fixes below are compatible with both versions, so apply them now and the later migration is mostly a TargetFramework bump.

Backticks in verbatim strings (the big one — breaks compilation under .NET 9). Detect:
```
grep -rn '@"[^"]*`' --include="*.cs"
```
Typically JavaScript template literals embedded in C# @"..." strings. Fix by converting to JS string concatenation (see below).
ImplicitUsings + explicit Main: projects that define their own Main and have <ImplicitUsings>enable</ImplicitUsings> can hit CS0017 (multiple entry points) on .NET 9 — set <ImplicitUsings>disable</ImplicitUsings> in those projects.

TestData compilation: test projects with .cs files under TestData\ compile them by accident. Exclude:

<ItemGroup>
  <Compile Remove="TestData\**\*.cs" />
  <None Include="TestData\**\*" />
</ItemGroup>

Note (don't yet update) packages below the minimums listed in Mode B.

Mode B: Completing the migration (on .NET 9)

<TargetFramework>net9.0</TargetFramework> in all .csproj files.
Update packages — minimums that matter here:
- Microsoft.CodeAnalysis.* (CSharp.Workspaces, Workspaces.MSBuild): 4.12.0+
- Microsoft.Build.Locator: 1.7.8+
- System.Text.Json: 9.0.0+
- Microsoft.CodeAnalysis.Workspaces.MSBuild was implicitly available on .NET 8 but often needs an explicit PackageReference on .NET 9 (CS0234 on Microsoft.CodeAnalysis.MSBuild is the symptom).
Apply all Mode A fixes if not already done.
dotnet clean && dotnet restore && dotnet build && dotnet test.

The template-literal fix (condensed)

CS1002/CS1056/CS1010 in a file that embeds JavaScript = backtick template literals inside a verbatim string.

// Before (breaks on .NET 9):
return @"html += `<div class=""result"">${value}</div>`;";

// After (works on 8 and 9):
return @"html += '<div class=""result"">' + value + '</div>';";

Backticks → single quotes, ${expr} → ' + expr + ', keep "" for HTML attributes inside the verbatim string.

---name: dotnet-8-to-9description: Use when migrating a project from .NET 8 to .NET 9, or preparing .NET 8 code for that migration with only the .NET 8 SDK available (e.g. Claude for Web).---# .NET 8 → 9 MigrationTwo modes — pick by what SDK is available:## Mode A: Pre-migration prep (still on .NET 8)Use this in environments without the .NET 9 SDK. All fixes below are compatible with both versions, so apply them now and the later migration is mostly a TargetFramework bump.1. **Backticks in verbatim strings** (the big one — breaks compilation under .NET 9). Detect: ```bash grep -rn '@"[^"]*`' --include="*.cs" ``` Typically JavaScript template literals embedded in C# `@"..."` strings. Fix by converting to JS string concatenation (see below).2. **ImplicitUsings + explicit Main**: projects that define their own `Main` and have `<ImplicitUsings>enable</ImplicitUsings>` can hit CS0017 (multiple entry points) on .NET 9 — set `<ImplicitUsings>disable</ImplicitUsings>` in those projects.3. **TestData compilation**: test projects with `.cs` files under `TestData\` compile them by accident. Exclude: ```xml <ItemGroup> <Compile Remove="TestData\**\*.cs" /> <None Include="TestData\**\*" /> </ItemGroup> ```4. **Note (don't yet update) packages below the minimums** listed in Mode B.## Mode B: Completing the migration (on .NET 9)1. `<TargetFramework>net9.0</TargetFramework>` in all .csproj files.2. Update packages — minimums that matter here: - `Microsoft.CodeAnalysis.*` (CSharp.Workspaces, Workspaces.MSBuild): **4.12.0+** - `Microsoft.Build.Locator`: **1.7.8+** - `System.Text.Json`: 9.0.0+ - `Microsoft.CodeAnalysis.Workspaces.MSBuild` was implicitly available on .NET 8 but often needs an **explicit** PackageReference on .NET 9 (CS0234 on `Microsoft.CodeAnalysis.MSBuild` is the symptom).3. Apply all Mode A fixes if not already done.4. `dotnet clean && dotnet restore && dotnet build && dotnet test`.## The template-literal fix (condensed)CS1002/CS1056/CS1010 in a file that embeds JavaScript = backtick template literals inside a verbatim string.```csharp// Before (breaks on .NET 9):return @"html += `<div class=""result"">${value}</div>`;";// After (works on 8 and 9):return @"html += '<div class=""result"">' + value + '</div>';";```Backticks → single quotes, `${expr}` → `' + expr + '`, keep `""` for HTML attributes inside the verbatim string.

Frequently asked questions

Dotnet 8 to 9