What does "[FIRApp registerAsConfigurable:]: unrecognized selector sent to class" error mean?

[Russ Jowell]

I'm working on a Xamarin.Forms app with Firebase Auth integration. I've set up Dependency Service for Android and iOS to create a new user when prompted. The Android dependency works fine, but whenever I call any 'Auth' method in my iOS dependency, the app crashes on startup with the following error thrown from my "Firebase.Core.App.Configure()" line in my delegate file:

 Foundation.MonoTouchException has been thrown

 

 Objective-C exception thrown. Name: NSInvalidArgumentException Reason:

 -[FIRApp setGetTokenImplementation:]:unrecognized selector sent to instance 0x282d3d1a0

...followed by a mile-long stack trace

  My current iOS Dependency code is below:

    using System;

    using Xamarin.Forms;

    using ActNearMe; //name of my app

    using Firebase.Auth;

    using Firebase.InstanceID;

    using Firebase.Core;

    using System.Collections.Specialized;

    using System.Net;

    using System.Threading.Tasks;

    [assembly: Dependency(typeof(IFirebaseInterface))]

    namespace ActNearMe.iOS

    {

        public class FirebaseInterface : IFirebaseInterface

        {

        WebClient client = new WebClient();

        NameValueCollection sendingData;

        public void CreateNewUser(string email, string password, NameValueCollection userData)

        {

            //sendingData = userData;

            //Anytime I call anything with Auth here, the app won't even load.

            Console.WriteLine(Auth.CurrentVersion);

            //Auth.DefaultInstance.CreateUser(email, password,(authResult, error) => { 

            /*client.UploadValuesCompleted += (sender, e) =>

            {

                Console.WriteLine("it's done!");

            };

            client.UploadValuesAsync(new Uri("http://www.cvx4u.com/anm_web_services/create_user.php"), sendingData);

            */

           //});

        }

        }

    }

Here is my error log:

    2019-04-15 10:18:53.724 ActNearMe.iOS[6964:1670900] +[FIRApp    registerAsConfigurable:]: unrecognized selector sent to class 0x1060d1bb8

    2019-04-15 10:18:53.724 ActNearMe.iOS[6964:1670900] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[FIRApp registerAsConfigurable:]: unrecognized selector sent to class 0x1060d1bb8'

    *** First throw call stack:

    (0x22401c518 0x2231f79f8 0x223f3e2c4 0x224021d60 0x2240239fc 0x2231f9ffc 0x2231fbe54 0x106626390 0x106638314 0x106637370 0x10663742c 0x1066266d8 0x10662b2a0 0x106625044)

    libc++abi.dylib: terminating with uncaught exception of type NSException

    Application 'com.russjowell.actnearme' terminated.

    Launched application 'com.russjowell.actnearme' on 'iPhone (2)' with pid 6964