Flutter — Undefined class ‘FirebaseUser’

In the newest version of firebase_auth, the class FirebaseUser was changed to User

Starting from Version firebase_auth 0.18.0:

In the newest version of firebase_auth, the class FirebaseUser was changed to User, and the class AuthResult was changed to UserCredential. Therefore change your code to the following:

Future<User> currentUser() async {
      final GoogleSignInAccount account = await googleSignIn.signIn();
      final GoogleSignInAuthentication authentication =
          await account.authentication;
      final GoogleAuthCredential credential = GoogleAuthProvider.credential(
          idToken: authentication.idToken,
          accessToken: authentication.accessToken);
      final UserCredential authResult =
          await _auth.signInWithCredential(credential);
      final User user = authResult.user;
      return user;
    }

FirebaseUser changed to User

AuthResult changed to UserCredential

GoogleAuthProvider.getCredential() changed to GoogleAuthProvider.credential()

onAuthStateChanged which notifies about changes to the user's sign-in state was replaced…