Newtonsoft.Json.dll is a popular open-source library developed by James Newton-King for working with JSON data in .NET applications. It provides a range of functionalities, including reading and writing JSON, serializing and deserializing .NET objects to JSON, LINQ to JSON, and more. It is widely used in various .NET projects and is available on NuGet, a package manager for the .NET platform.
If you encounter errors related to Newtonsoft.Json.dll, it could be due to the library being missing, outdated, or corrupted. To fix these errors, you can try reinstalling the library, updating it to the latest version, or repairing the installation of the application that uses it.