I can't log in without authetificator app, but I can't log in INTO the APP

Hi @Kao Meet, 

Thank you for posting your question in the Microsoft Q&A forum.                 

Regarding that you can't log in to your account due to Microsoft Authenticator. I’d like to ask a quick questions to better understand your situation and assist you effectively:        

Could you please clarify whether you are an end user or an admin?               

If you are an end user I would recommend you contact your account's Admin to reset your MFA settings through the Microsoft Entra Admin Center. Ask your administrator to follow these steps:       

1. Sign in to Microsoft Entra admin center with the admin account  
2. Go to Users 
3. Select the affected user account  
4. Open Authentication methods  
5. Revoke sessions  
6. Select Require re‑register MFA  
7. Save the changes                

Revoke MFA sessions and require re-register in the Microsoft Entra admin center                   

You could refer this article for a better view: Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID |…  

If you’re unsure who the Global Admin is within your organization, you can find guidance on locating them here: How do I find my Microsoft 365 admin? - Microsoft Support.                       

Please note that forum moderators have no control over user accounts, especially when it comes to logging in to your account, resetting your password, changing your access, etc.                  

Thank you again for your time and understanding. While my initial response may not resolve the issue immediately, I’d like to gather more details about your situation so I can assist you more effectively.              

I really appreciate your patience, and I’m here to help. Looking forward to your response!                        

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".                 

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The account is locked in an MFA loop where Microsoft Authenticator is the only sign-in method and is no longer accessible. To break this loop, the MFA settings must be reset by an administrator or by Microsoft support, depending on the role and how many admins exist.

Use the path that matches the situation:

1. If this is a work/school (business) account and there is another admin

• Ask another global admin in the tenant to reset MFA:
  • Go to Microsoft Entra admin center (https://entra.microsoft.com).
  • Navigate to Users → All users → [select the affected user] → Authentication methods.
  • Select Require re-register multifactor authentication.
  • Next sign-in will prompt to set up Authenticator again on the new device.

2. If this is a work/school account and this is the only admin

• Microsoft Data Protection team must reset the admin’s MFA.
• Call Microsoft support using the regional Customer service phone numbers.
• When navigating the phone/IVR system, clearly state:
  • The problem: “Authenticator” / “lost access to Authenticator and MFA loop”.
  • Product: “Office 365 for business” or “Microsoft 365 for business”.
  • Account type: “Company account”.
  • Role: “I am the only administrator; there is no other admin.”
  • Request: “I need to create a service request and speak with the Data Protection team to reset my MFA.”
• Be prepared to verify identity and tenant ownership; the Data Protection team will then revoke/reset MFA for the admin account so new methods (including Authenticator on the new device) can be registered.

3. If support is hard to reach via phone

• Create a temporary trial Microsoft 365 tenant:
  • Sign up for a free Microsoft 365 trial and complete tenant creation.
  • Go to the Microsoft 365 Admin Center of this new tenant.
  • Use Help & support to open a ticket.
  • In the ticket, explain that access is needed for a different, existing tenant where the admin is locked out due to Authenticator-only MFA.
  • Ask to be connected to the Data Protection team for the original tenant.
• After the original tenant issue is resolved, cancel the trial subscription to avoid charges.

4. If this is an end user (non-admin) business account

• Contact the organization’s IT admin or help desk and ask them to:
  • Reset MFA / require re-registration for the account in Microsoft Entra admin center.
• After reset, sign in again and reconfigure Authenticator on the current device.

5. If repeated sign-in attempts are now blocked

• Microsoft Entra MFA may temporarily block sign-ins after many failed attempts.
• Wait before trying again, or use a different MFA method if one exists.
• If malicious activity is suspected, the tenant admin should review Microsoft Entra sign-in logs.

There is no self-service way to bypass or disable Authenticator when it is the only configured method and the app is no longer accessible; an admin or Microsoft support (Data Protection team) must reset MFA.

References:

• Common problems with two-step verification for a work or school account
• Authenticator Did Not Complete Login
• I cant log in to my business account because it is requiring Authenticator app which I do not have - 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
• How Do I Regain Access to My Account After Losing Access to Microsoft Authenticator? (Urgent Request). - Microsoft Q&A
• Microsoft authenticator sending me into a spiral - Microsoft Q&A
• Requesting a Tenant Admin MFA Reset - Microsoft Q&A