Upgrade flow not working in 9.0.0

[j-gironda]

The upgrade flow from anonymous to a full account is broken in 9.0.0.

Even with the enableAnonymousUsersAutoUpgrade() option set, the flow always returns RESULT_OK and creates a new user with a new UID, instead of linking the account to the existing anonymous user UID.

It happens no matter how setCredentialManagerEnabled is configured.

Downgrading to 8.0.2 solves it.

[ViditBabele]

Faced this in production, what should be the firebase bom wrt to 8.0.2

[oliverClimbs]

FirebaseUI Anonymous Account Upgrade Creates New User Instead of Linking

Summary

When using enableAnonymousUsersAutoUpgrade() with Google sign-in, FirebaseUI creates a new user account with a different UID instead of linking the anonymous account. This causes data loss and orphaned anonymous accounts in Firebase Console.

Environment

• FirebaseUI version: 9.0.0
• Firebase Auth SDK version: (latest as of Jul 2025)
• Platform: Android

Steps to Reproduce

1. Start app and sign in anonymously
2. Create some data associated with anonymous user
3. Click "Change Account" and select Google sign-in
4. Complete Google authentication
5. Observe that a new user is created instead of upgrading the anonymous account

Expected Behavior

• Anonymous account should be upgraded/linked to Google credentials
• User ID should remain the same
• All data associated with anonymous account should be preserved
• No orphaned anonymous accounts in Firebase Console

Actual Behavior

• New user account is created with different UID
• Original anonymous account data becomes inaccessible
• Anonymous account remains in Firebase Console as orphaned
• isNewUser returns true indicating a brand new account

Code Configuration

// Configure authentication providers
val providers = arrayListOf(
    AuthUI.IdpConfig.GoogleBuilder().build(),
    AuthUI.IdpConfig.EmailBuilder().build()
)

// Create sign-in intent
val signInIntent = AuthUI.getInstance()
    .createSignInIntentBuilder()
    .setAvailableProviders(providers)
    .setTheme(R.style.Theme_Ibex)
    .setLogo(R.drawable.ic_logo)
    .enableAnonymousUsersAutoUpgrade()
    .setCredentialManagerEnabled(false)
    .build()

Log Evidence

Scenario 1: Google Sign-in (BROKEN)

19:05:01.626  I  Anonymous sign-in successful - new userId: dHIGzs88o6Mvlcwc8hpwKr13Qfw1, isAnonymous: true
19:05:11.394  D  Current user: dHIGzs88o6Mvlcwc8hpwKr13Qfw1, isAnonymous: true
19:05:11.395  D  Launching FirebaseUI directly
19:05:23.058  I  Auth state changed - oldUserId: dHIGzs88o6Mvlcwc8hpwKr13Qfw1, newUserId: kby4JrZk4TN71jSoHuJWSmZxl5K2
19:05:23.257  D  handleSignInResult: resultCode=-1, responseErrorCode=null
19:05:23.257  I  Sign-in successful - userId: kby4JrZk4TN71jSoHuJWSmZxl5K2, isNewUser: true, email: xxx@gmail.com, isAnonymous: false

Result: Different UID, data lost, isNewUser: true

Scenario 2: Email/Password Sign-in (WORKING CORRECTLY)

18:22:51.626  I  Anonymous sign-in successful - new userId: u9UkxZuDRBM67By8krgOSyYOED92, isAnonymous: true
18:23:00.002  D  Current user: u9UkxZuDRBM67By8krgOSyYOED92, isAnonymous: true
18:23:00.003  D  Launching FirebaseUI directly
18:23:23.424  D  handleSignInResult: resultCode=-1, responseErrorCode=null
18:23:23.425  I  Sign-in successful - userId: u9UkxZuDRBM67By8krgOSyYOED92, isNewUser: false, email: xxx@x.com, isAnonymous: false

Result: Same UID preserved, data intact, isNewUser: false

Additional Finding: Provider Configuration Dependency

The bug's behavior depends on which authentication providers are configured:

• When ONLY email provider is configured: Email sign-in ALSO fails to link (creates new user)
• When BOTH email and Google providers are configured: Email sign-in works correctly, but Google sign-in still fails

This suggests the issue is in FirebaseUI's provider configuration handling logic, not in the individual authentication providers themselves.

Additional Information

Merge Conflict Handler Never Triggered

The app includes proper merge conflict handling, but it's never executed:

response.error?.errorCode == ErrorCodes.ANONYMOUS_UPGRADE_MERGE_CONFLICT -> {
    Log.w("Sign-in failed: Account merge conflict")
    handleMergeConflict(response)
}

This confirms the issue is NOT a merge conflict - FirebaseUI is creating entirely new accounts instead of attempting to link.

Attempted Solutions

1. Disabled Credential Manager with setCredentialManagerEnabled(false) - no effect
2. Verified SHA-1 fingerprints in Firebase Console - correct
3. Attempted to disable Google provider - breaks email sign-in functionality

Impact

• Data Loss: Users lose all data created while anonymous
• User Experience: Users must start over after signing in
• Backend Pollution: Orphaned anonymous accounts accumulate in Firebase Console

Related Issues

• Handling anonymous user upgrade merge conflicts: Wrong error code #1435 - Different issue about merge conflict error codes
• Anonymous user and account conversion to permanent account #123 - General discussion about anonymous account conversion

Workaround

Currently keeping both providers enabled but warning users to use email/password authentication only, as it correctly preserves the anonymous user's UID when Google provider is also present.

Request

Please investigate why enableAnonymousUsersAutoUpgrade() creates new accounts instead of linking when using Google sign-in. This appears to be a critical bug causing data loss for users.