How to enable Nullable Reference Types feature of C# 8.0 for the whole project

c# visual-studio visual-studio-2019 c#-8.0 nullable-reference-types

Sergey V · Dec 5, 2018 · Viewed 29.4k times · Source

According to the C# 8 announcement video the "nullable reference types" feature can be enabled for the whole project.

But how to enable it for the project? I did not find any new appropriate option in the Project Properties window in Visual Studio 2019 Preview 1.

Can it be enabled for 'legacy' .csproj projects if the C# language version is changed to 8.0?

Answer

In Visual Studio 16.2 (from preview 1), the property name is changed to Nullable, which is simpler and aligns with the command line argument.

<PropertyGroup>
  ...
  <Nullable>enable</Nullable>
  <LangVersion>8.0</LangVersion>
</PropertyGroup>

Note that if you're targeting netcoreapp3.0 or later, you don't need to specify a LangVersion of 8, as that is the default in .NET Core 3.

For older Visual Studio versions: