.Net application – C# – resolving error – S8370 Feature ‘nullable reference types’ is not available in C# 7.3. Please use language version 8.0 or greater.

Hi All,

Greetings for the day!!!

Today new issue and solution. Today’s issue bit different than Microsoft 365. Its related to C#.

I am not C# expert but still sharing since it save time.

Background

• I am working .NET application where I am accessing Graph APIs.
• I am using Visual Studio 2022.
• I am using .Net Framework 4.8. This is the default framework coming for me. Though I was looking for .NET framework 8.0.

• For storing client app id and other details I am using “Settings” class which is derived from “System.Configuration.ApplicationSettingsBase” class.

[global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
[global::System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.VisualStudio.Editors.SettingsDesigner.SettingsSingleFileGenerator", "11.0.0.0")]
internal sealed partial class Settings : global::System.Configuration.ApplicationSettingsBase
{

    private static Settings defaultInstance = ((Settings)(global::System.Configuration.ApplicationSettingsBase.Synchronized(new Settings())));

    public static Settings Default
    {
        get
        {
            return defaultInstance;
        }
    }
}

• I have added my custom class called “GraphHelper.cs” for authenticating Graph APIs.
• In this class I have “Setting” class nullable instance as

namespace MS_Graph_Demo
{
    internal class GraphHelper
    {
        // Settings object
        private static Settings? _settings;
        // App-ony auth token credential
        private static ClientSecretCredential? _clientSecretCredential;
    }//cs
}//ns

• Here, in above code on declaration of “Settings” instance I am getting an error as

Issue

Error (active) CS8370 Feature ‘nullable reference types’ is not available in C# 7.3. Please use language version 8.0 or greater.

Cause

• My project is configured for C# 7.3, we need to change the language version.

Solution

• Once we have configured our project for C# 8.0, and with Nullable Reference Types enabled, Roslyn, the C# compiler, will understand nullability annotations. It will give code analysis based on them.
• We can enable “nullable reference types” feature for the whole project.
• To enable Nullable Reference Types for all code in a project, we need to update the .CSPROJ file
• Close the solution in Visual Studio.
• Open the .CSPROJ file in text editor (I am opening in NOTEPAD) and add the below lines in .CSPROJ file as

<Nullable>enable</Nullable>
<LangVersion>8.0</LangVersion>

• Open the solution in Visual Studio.
• Build it again and solution get successfully build.

Have a wonderful day ahead!!!

Thanks for reading !!!

REFERENCES

• Configure C# language version – https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/configure-language-version