React Ionic and Google Firebase auth errors when using ios mobile application

Hi All,
I am currently having some issues trying to integrate Google Firebase authentication into a React Ionic mobile application. So far I have been able to set up the app to run correctly on both web and android but am running into repeated issues with IOS. The code runs correctly for Firebase auth login on android does not seem to be running on IOS.

The initial call to “signInWithEmailAndPassword” seems to work fine and returns “auth/multi-factor-auth-required” but any time I try to make a call to “verifyPhoneNumber” on ios I will receive the response of “Firebase: An internal AuthError has occurred. (auth/internal-error)”, there are no further details provided.

//Firebase setup in seperate file with code like these 2 lines 
const firebaseAuth = app.auth();

.signInWithEmailAndPassword(email, password)
.then(function (user) {
        //other code
.catch(function (error) {
        if (error.code === "auth/multi-factor-auth-required") {
            let resolver = error.resolver;
            setTimeout(() => {
                dispatch(phoneAuth(appVerifier, resolver));
            }, 2000);
      } else {
          //other code

var phoneInfoOptions = {
    var phoneInfoOptions = {
      multiFactorHint: resolver.hints[0],
      session: resolver.session,
    var phoneAuthProvider = new firebase.PhoneAuthProvider();
      .verifyPhoneNumber(phoneInfoOptions, appVerifier)
      .then(function (verificationId) {
        console.log("verify Id recieved");
      .catch((error) => {

Things I have checked/tried so far are:
followed all steps in firebase docs
Setup ios app in firebase console and followed the steps listed

Has anyone run into issues like this previously and has any advice on what I could check next?


Not sure if this is a solution, but would it matter if you use fat-arrow instead of function? I cannot say if the // other code depends on this. I am not a react coder so it can also be my lack of understanding.

I do know, but also unrelated maybe, that login with popup does not work on iOS, as you need to use redirect - using the web sdk.