Authenticator not working on new phone

Question

Bought a new Samsung, copied data over.

Authenticator not working.

Deleted the app and reinstalled it before seeing not to do so.

Old phone not available.

Answer 1

Because the old phone is no longer available and the app was deleted/reinstalled on the new phone, the existing Microsoft Authenticator registrations are effectively lost on the device. Recovery depends on what account type is involved and what other verification methods are still configured.

Follow the applicable path:

1. If this is a personal Microsoft account

• Go to the two-step verification area of the Account Security page while signed in on a trusted browser or device.
• Turn off verification for the old Authenticator registration so notifications stop going to the missing device.
• Re-add Microsoft Authenticator on the new phone:
  • Install the app.
  • In the app, choose Add account → Personal Microsoft account and sign in.
  • This re-registers the new device so push notifications work again.

2. If this is a work or school account and another MFA method still works (SMS/phone/email)

• Sign in to Microsoft 365 (for example via office.com) using the remaining working MFA method.
• Go to the Security info / Additional security verification page.
• Delete the old phone/Auth app entry.
• Add a new sign-in method (phone and/or Microsoft Authenticator) and complete setup on the new Samsung.

3. If this is a work or school account and no other MFA method works

• A tenant/global admin must reset MFA for the account so that MFA methods can be configured again. They can use the “Require re-register MFA” option described in the admin documentation.
• If the locked-out account is the only global admin on the tenant, Microsoft’s Data Protection team must be engaged via a support ticket or phone support to verify identity and restore access, as described in the referenced Q&A answers.

4. For future device changes

• When moving to a new phone, first add and verify the new phone/Auth app as a sign-in method, then remove the old device from the Account Security or My Apps / company portal pages so notifications and MFA prompts no longer go to the old device.

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References:

• Microsoft Authenticator FAQs
• Troubleshoot problems with Microsoft Authenticator
• Use a screen reader to set up and troubleshoot multifactor authentication
• I need to reset my mfa methods - Microsoft Q&A
• I have a Micrsoft business account and I am the admin and the only user registered under this account. I can't log in because i have replaced my phone and the authenticator doesn't work. - Microsoft Q&A
• Requesting a Tenant Admin MFA Reset - Microsoft Q&A
• Cannot authenticate with E-mail when logging into Microsoft Authenticator(iOS). - Microsoft Q&A
• Severity A Situation - Locked out of global admin account (MFA) - business down - Microsoft Q&A