CS0246 🟪 .NET

error CS0246: The type or namespace name 'X' could not be found (are you missing a using directive or an assembly reference?)

The compiler doesn’t know the type — missing using, missing NuGet package/project reference, or a target framework mismatch.

Seen on: .NET

Meaning

After moving code between projects, the reference or package often isn’t added. Packages that don’t support the target framework also produce CS0246 after restore warnings.

Common causes

  • Missing using directive
  • NuGet package/project reference not added
  • Package doesn’t support the target framework
  • Typo or wrong casing

⚡ Quick fix

  1. Add the using or reference (dotnet add package/reference)
  2. Restore and check warnings (NU1701, NU1202)
  3. Check the type’s namespace

Detailed fix by platform

Shell

  1. csharp
    dotnet add package Newtonsoft.Json
dotnet add reference ../App.Core/App.Core.csproj
dotnet restore

How to diagnose

  1. Namespace — Where is the type?
  2. References — Package/project referenced?
  3. Framework — Supported?

🔧 Still not fixed?

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