Firebase Convert Anonymous User Account to Permanent Account Error

Question

Using Firebase for web I can successfully create an anonymous user. I can also create a new email/password user. But when trying to convert an anonymous user to a email/password user I get error:

auth/provider-already-linked
User can only be linked to one identity for the given provider.

Firebase documents the procedure here under section "Convert an anonymous account to a permanent account" here: https://firebase.google.com/docs/auth/web/anonymous-auth

Here's the account link code. Anonymous user is signed in.

return firebase.auth().createUserWithEmailAndPassword(email, password).then(newUser => {

    // Credential is being successfully retrieved. Note "any" workaround until typescript updated.
    let credential = (<any>firebase.auth.EmailAuthProvider).credential(email, password);

    firebase.auth().currentUser.link(credential)
        .then(user => { return user; })
        .catch(err => console.log(err)); // Returns auth/provider-already-linked error.
});

Laurent Meyer · Accepted Answer · 2024-04-21 09:27:06Z

72

You should not call createUserWithEmailAndPassword to upgrade the anonymous user. This will sign up a new user, signing out the currently signed in anonymous user.

All you need is the email and password of the user. IDP providers (e.g. Google, Facebook), on the contrary, will require to complete their full sign in flow to get their tokens to identify the user. We do recommend to use linkWithPopup for these, though.

Example:

// (Anonymous user is signed in at that point.)

// 1. Create the email and password credential, to upgrade the
// anonymous user.
var credential = firebase.auth.EmailAuthProvider.credential(email, password);

// 2. Links the credential to the currently signed in user
// (the anonymous user).
firebase.auth().currentUser.linkWithCredential(credential).then(function(user) {
  console.log("Anonymous account successfully upgraded", user);
}, function(error) {
  console.log("Error upgrading anonymous account", error);
});

Let me know if that works!

edited Apr 21, 2024 at 9:27

Laurent Meyer

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answered Aug 23, 2016 at 5:27

TMSCH

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5 Comments

Xavier V. Over a year ago

firebase.User.prototype.link is deprecated. Please use firebase.User.prototype.linkWithCredential instead.

Peza Over a year ago

Thanks for this answer - the same logic applies in client mobile apps using Firebase. I was experiencing the same issue in an iOS app, and this logic fixed it. The Firebase docs on this aren't very clear - they should highlight this (if anyone from Google reads this).

BlazeFast Over a year ago

Docs did not explain well at all that linkWithCredential is basically a replacement for createUserWithEmailAndPassword.

BHAR4T Over a year ago

is currentUser is predefined?

CharlesC Over a year ago

Latest version is AuthCredential authCredential = EmailAuthProvider.getCredential(email: email, password: password);

mrkiril · Accepted Answer · 2020-12-29 13:07:48Z

3

After you log in as an Anonymous user, run this code to raise Popup and connect your anon user wit some OAUTH provider

const provider = new firebase.auth.FacebookAuthProvider()
firebase.auth().currentUser.linkWithPopup(provider)
console.log(provider)

answered Dec 29, 2020 at 13:07

mrkiril

1,25117 silver badges11 bronze badges

Comments

Lance Samaria · Accepted Answer · 2022-02-25 19:46:38Z

0

For iOS, Swift 5 to create a credential use

EmailAuthProvider.credential(withEmail: , password: )

example:

let credential = EmailAuthProvider.credential(withEmail: emailTextField.text!, password: passwordTextField.text!)
        
Auth.auth().currentUser?.link(with: credential, completion: { (authDataResult: AuthDataResult?, error) in

    // ...
})

answered Feb 25, 2022 at 19:46

Lance Samaria

19.8k24 gold badges131 silver badges319 bronze badges

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