If you’ve stumbled upon a NuGet error, a legacy project dependency, or an old Stack Overflow thread mentioning System.Runtime.CompilerServices.Unsafe version 4.0.4.1, you might be wondering: Do I need to download this specific version?
The short answer is: But let’s break down what this package is, why version 4.0.4.1 exists, and how to handle it safely in 2025. If you’ve stumbled upon a NuGet error, a
If a project requires 4.0.4.1, NuGet will fetch it from nuget.org automatically when you run: a legacy project dependency
If you control the project, run:
Understanding System.Runtime.CompilerServices.Unsafe Version 4.0.4.1: Should You Download It? why version 4.0.4.1 exists