Error 500121

Question

Im admin of an business account and cant login because my Authenticator dont receive the notificactions, when

i try to use a code it appears the error 500121. What i can do? , i tried to contact sales support but i didnt got attended

Answer 1

Hi @Luis Angel Navarro Puente,

Thank you for your response.

If reaching support via phone cannot be applied to your situation, there is still a workaround, you might consider registering for a new tenant by signing up for a trial subscription.

To set up a trial tenant, please follow these steps:

• Visit Microsoft 365 Business Plans and Pricing | Microsoft 365and select "Try for free". This would allow you to create a new tenant following the prompts provided. Once set up, you can access the admin console of the new tenant and submit a support ticket requesting to speak with the Data Protection team on behalf of your previous tenant.
• Create a support ticket: In the Microsoft 365 Admin Center > Help & Support.
• In your ticket description, you'll need to clearly explain that you're trying to regain access to your previous Microsoft 365 tenant and need help from the Data Protection team. Here's a message you can use or adapt:

"Hello, I’m currently unable to access my previous Microsoft 365 tenant due to losing MFA access. I’m the only global admin, but I’m locked out and unable to generate a QR code or bypass MFA.

I created this new tenant solely to request assistance. I kindly ask to be connected with the Data Protection team to verify my identity and help me recover access to the original tenant.

This is urgent, as I rely on Microsoft 365 for my work and have been unable to operate for several days. I’m available to provide any documentation or verification needed to support the recovery process."

Important notes:     

• This new trial tenant will not give you access to any of the data or settings in your original locked tenant. It is solely a temporary means to contact Microsoft support.    
• The resolution time might be longer as you are contacting support from a different tenant.    
• Remember to cancel the trial subscription for the new tenant once your issue with the original account is resolved to avoid any unintended charges. Cancel your Microsoft business subscription in the Microsoft 365 admin center | Microsoft Learn.

I hope the information provided helps guide you in the right direction. Although I’m unable to take direct action, I sincerely hope that the steps and recommendations I’ve shared can support you through the process.

If my response can help you reach the appropriate support successfully, you may consider marking it as an accepted answer. This can make it easier for other community members experiencing similar situations to quickly identify helpful guidance and solutions and ensures that the thread is more valuable for others searching for the same issue.

Thank you again for your time and for your continued cooperation.

Answer 2

hi Luis Angel Navarro Puente,
Error 500121 is usually related to Microsoft Entra ID / MFA authentication problems, often when:

• the Authenticator app is not receiving push notifications,

the MFA registration is corrupted,

or the device token is no longer trusted.

Since you are the admin account, try these things first:

In Microsoft Authenticator:

Make sure notifications are enabled on the phone

  Disable battery optimization for the app
  
     Verify date/time on the phone is correct
     
     Try using:
     
        “Use verification code” instead of push approval.
        
        Try logging in from:
        
        ```yaml
        https://mysignins.microsoft.com/security-info
        ```
        
        to re-register MFA methods.
        

If you cannot access the account at all:

another Global Admin in the tenant may need to:

reset your MFA methods,

  revoke sessions,
  
     or temporarily disable MFA for your account.
     

If you are the ONLY admin and fully locked out, you may need Microsoft Data Protection / Account Recovery support to verify tenant ownership and regain access.
If my answer is useful for you, please hit Accept the answer to support me.

Thank you so much,

Answer 3

Hi @Luis Angel Navarro Puente,

Thank you for taking the time to share your experience. I hope this response reaches you in time and helps bring some clarity.

The error code 500121 is generally related to a failure in the multi‑factor authentication (MFA) process during sign‑in. This typically means that although the account credentials (username and password) may be correct, the second step of verification could not be successfully completed. In your case, since the Microsoft Authenticator app is not receiving notifications, the authentication request may not be reaching your device or may not be getting approved in time. As a result, the system is unable to confirm your identity through MFA, and access to the account is blocked until the authentication method can be successfully completed or reset.

For admin access recovery, the available options are as follows:

---

Option 1: Contact another IT administrator in your organization (if available)

Please check if there are other IT admins who still have access and share with them the steps outlined in the article Manage user authentication methods for Microsoft Entra multifactor authentication. This will help them assist you in resetting your MFA settings and restoring access to the account.

Once the other admin completes this process, your previous sign-in sessions will be cleared, and the next time you log in, you will be prompted to set up MFA again from scratch.

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Option 2: Contact Microsoft Data Protection Support by phone

If you are the sole global administrator, you will need assistance from Microsoft’s Data Protection team. They will verify domain ownership and other required information in order to restore your access.

To reach the team, you can try calling your regional Microsoft support hotline here: Global Customer Support.

During the phone call, you will need to provide the information associated with your subscription, such as your company name, billing details, phone number, and an alternate email address, etc. This information allows the Data Protection team to verify your identity and securely assist you in regaining access to your administrator account.

In some regions, the initial interaction may be automated, so here’s a general idea of how the conversation might go to help you prepare:

(When you call the support number, you may hear an introduction of about 30 seconds such as "you can visit the link...". You can ignore this introduction and wait until you are presented with the options. Then press "1" as a business email user, and again "1" for technical help.)

In some countries, it is an automated conversation like:

IVR: What kind of problem are you concerned about?

You: Authenticator.

IVR: What kind of product do you use?

You: Office 365 for business.

IVR confirmation: education or company account?

You: For companies

IVR: Are you an administrator?

You: Yes.

IVR: Do you have another administrator in your organization?

You: No.

IVR: Do you need a... Service request?

You: Yes. I need to create a ticket. Please send me directly to the Data Protection Team.

Please note that forum moderators do not have access to user account settings and cannot assist with logging in, resetting passwords, or changing access rights. While we do not have access to internal systems or administrative tools required to resolve account-specific or backend-related issues, we’ll continue doing our best to support you within the scope of our responsibilities.

I hope this helps you regain access to your account quickly. I'm glad to assist and truly hope the information provided has been useful. Please feel free to reach out anytime if you need further assistance.

If you find my post useful, kindly consider upvoting it. Doing so can assist others in the community who may have similar questions in finding solutions more quickly.

Thank you for your kindness and contributions to the forum.

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