Firebase onAuthStateChange() state does not change Code Answer

Hello Developer, Hope you guys are doing great. Today at Tutorial Guruji Official website, we are sharing the answer of Firebase onAuthStateChange() state does not change without wasting too much if your time.

The question is published on by Tutorial Guruji team.

I am trying to login the user to my app. I expect when the user enters details and signs in, to be redirected and to console.log(user); account details. The problem is that console just shows Not logged in even after I try to login. Regarding the overall flow of the application, when the user successfully signs in, a token is sent from the cloud function which is displayed in the console. I do not understand what am I doing wrong here.

function signIn() {
  var usernameValue = document.getElementById("sign-in-username").value;
  var passwordValue = document.getElementById("sign-in-password").value;

  fetch("http://localhost:5001/.../europe-west3/api/login", {
    method: "POST",
    mode: "cors",
    headers: {
      "Content-type": "application/json",
    body: JSON.stringify({
      username: usernameValue,
      password: passwordValue,
    .then((res) => {
      return res.json();
    .then((data) => {
    .catch((error) => console.log("ERROR"));

The authentication state does not change.

auth.onAuthStateChanged(function (user) {
  if (user) {
    window.location.href = "user.html";
  } else {
    console.log("Not logged in");


If you some sort of API endpoint to sign in a user, that will never have an effect on the auth state observed by the Firebase SDK. The auth state observer is only going to trigger when you also use the Firebase SDK to sign in the user. For example, it triggers when you call methods like signInWithEmailAndPassword(), or any of the methods that start with “signIn”.

We are here to answer your question about Firebase onAuthStateChange() state does not change - If you find the proper solution, please don't forgot to share this with your team members.

Related Posts

Tutorial Guruji