How to reset MFA after deleting the authenticator app.

Question

I accidentaly deleted the Microsoft authenticator app on an old device and i cant access it with a new device, how could i reset MFA so i can get the new QR codes for the new device.

Answer 1

Because the Microsoft Authenticator app was deleted, the existing MFA registration must be reset so a new device can be enrolled. The exact steps depend on whether the account is a work/school (Microsoft Entra ID / Microsoft 365) account and whether there is an administrator available.

1. If this is a work or school (organizational) account and there is an admin available
   • Ask a Global Administrator in the tenant to require MFA re-registration for the account.
   • Admin steps (in Microsoft Entra ID):
     1. Go to the Azure portal and open Microsoft Entra ID.
     2. Select Users and then select the affected user.
     3. Under Manage, select Authentication methods.
     4. Select Require re-register multifactor authentication.
   • After this, sign in again; the sign-in flow will prompt to set up MFA from scratch and show a new QR code for Microsoft Authenticator.
2. If this is a work or school account and there is no other admin (only one global admin, now locked out)
   • This is a tenant lockout scenario. The MFA registration cannot be reset from the portal because no admin can sign in.
   • In this case, contact Microsoft support and have a ticket raised to the Data Protection team to reset the MFA methods and restore access. This is the only path when the sole global admin is locked out by MFA.
3. If this is a work or school account and there are already five authenticator devices registered
   • If the error is that five devices are already registered, delete some sign-in methods so the new device can be added:
     1. Go to https://aka.ms/mysecurityinfo and sign in.
     2. In Security info, delete one or more existing Authenticator app or other sign-in methods associated with old devices.
     3. Then add Microsoft Authenticator again and scan the new QR code when prompted.
   • If a passwordless sign-in method is configured, set up another two-factor method (SMS or phone call) first so it can be used to confirm deletion of the old authenticator method.
4. If this is a personal Microsoft account using Microsoft Authenticator
   • Re-register the device with the account in the app:
     1. Install Microsoft Authenticator on the new device.
     2. In the app, choose Add account → Personal Microsoft account.
     3. Sign in with the Microsoft account username and password; this re-registers the device and enables notifications/verification again.
   • If notifications were going to an old device, also remove the old device registration:
     • Go to the two-step verification area of the Account Security page and turn off verification for the old device, then set up the new device.
5. General guidance
   • Do not delete the authenticator app in the future while MFA is still required for the account. The app (or another MFA method such as SMS/call) must remain available as long as MFA is enforced.
   • If no alternative method (phone, SMS, backup admin) exists and sign-in is impossible, the only supported recovery path for work/school accounts is via Microsoft support and the Data Protection team.

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References:

• Can't set up MFA because five devices are already registered to use an authenticator app
• Microsoft Authenticator FAQs
• Use a screen reader to set up and troubleshoot multifactor authentication
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• I need to reset my mfa methods - Microsoft Q&A
• Requesting a Tenant Admin MFA Reset - Microsoft Q&A
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• Severity A Situation - Locked out of global admin account (MFA) - business down - Microsoft Q&A
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