'.NET Core 3 preview 4: 'AddNewtonsoftJson' is not defined

Using .NET Core 3 preview 4, the "API" template for a F# ASP.NET MVC project fails to build. This is without any changes to the template whatsoever.

This is the code that fails:

type Startup private () =
    member this.ConfigureServices(services: IServiceCollection) =
        // Add framework services.
        services.AddControllers().AddNewtonsoftJson() |> ignore

With error

...\Startup.fs(23,35): error FS0039: The field, constructor or member 'AddNewtonsoftJson' is not defined. Maybe you want one of the following: AddNewtonsoftJsonProtocol

It seems that there are changes coming for this - is it just being worked on and unusable right now?

f#.net-core-3.0

Solution 1:^[1]

In order to switch ASP.NET Core 3.0 back to use JSON.NET, you will need to reference the Microsoft.AspNetCore.Mvc.NewtonsoftJson NuGet package. That will contain the AddNewtonsoftJson extension method.

In C#, this would look like this:

services.AddControllers()
    .AddNewtonsoftJson();

So assuming that I understand enough of F#, I would say that your call would be correct if you have the package referenced in your project.

Solution 2:^[2]

Add package: Microsoft.AspNetCore.Mvc.NewtonsoftJson
Package details: https://www.nuget.org/packages/Microsoft.AspNetCore.Mvc.NewtonsoftJson
Call AddNewtonsoftJson() extension method as mentioned below

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllersWithViews().AddNewtonsoftJson();
    }

Solution 3:^[3]

It's work for me, Install the NewtonsoftJson package from NuGet "dotnet add package Microsoft.AspNetCore.Mvc.NewtonsoftJson --version 3.1.0" version 3.1.0 working for ASP.NET Core 3.0 and use the Following Code-

services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_3_0)
        .AddNewtonsoftJson(opt => {
            opt.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;
        });

Hope it's Working Fine, Thanks.

Solution 4:^[4]

For me this helped:

Code in Startup.cs

services.AddControllers().AddNewtonsoftJson(x => x.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore);

Upgrade all Nuget Packages to 3.1.8 (3.1.3 was not working)

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1
Solution 2	Rohit Jadhav
Solution 3
Solution 4	Simon Neubauer

'.NET Core 3 preview 4: 'AddNewtonsoftJson' is not defined

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Solution 4:[4]

Sources

Related Questions

Solution 1:^[1]

Solution 2:^[2]

Solution 3:^[3]

Solution 4:^[4]