dotnet add package Newtonsoft.Json --version 4.0.8. NuGet\Install-Package Newtonsoft.Json -Version 4.0.8.
: In Visual Studio, right-click your project, select Manage NuGet Packages , and search for "Newtonsoft.Json". download newtonsoft.json.dll for .net 4.0
Note: Newer versions like 13.0.3 also maintain compatibility with .NET 4.0. 2. Manual DLL Extraction dotnet add package Newtonsoft