C# solve class SessionExtensions problem in ASP.NET Core 2.1

Question

Task: I try to build shopping cart using session in .NET Core.

Error 1:

No overload for method 'Serialize' takes 1 arguments

Error 2:

Can't convert from string to 'Newtonsoft.Json.JsonReader'

In code => Deserialize<T>(value)

public static class SessionExtensions
{
    public static void Set<T>(this ISession session, string key, T value)
    {
        session.setString(key, JsonSerializer.Serialize(value));
    }

    public static T Get<T>(this ISession session, string key)
    {
        var value = session.GetString(key);
        return value == null ? default : JsonSerializer.Deserialize<T>(value);
    }
}

I try to pass one argument to Serialize() method, but I failed. Because this method takes at least two arguments are textWriter and object.