Error code 500121

Question

Error Code: 500121

Request Id: <PII removed>

Correlation Id: <PII removed>

Timestamp: 2026-07-31T17:52:31Z

Moved from: Microsoft Security | Microsoft Authenticator

Answer 1

Hi @Andrea Del Bianco, 

The 500121 error commonly occurs when a Multi-Factor Authentication (MFA) request is not successfully completed. This can happen if the authentication prompt is not approved, the request times out, an incorrect verification code is entered, or the Microsoft Authenticator registration on the device is no longer valid.  

The next steps will depend on whether you're signing in as an end user or as a Microsoft 365 administrator. If you are an end user, I recommend contacting your organization's IT administrator. They can reset your MFA registration and require you to set it up again. You can ask them to follow the guidance in the following article: Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID |…

In most cases, this process only takes a few minutes. It clears the existing MFA registration and active authentication sessions. The next time you sign in, you'll be prompted to register Microsoft Authenticator again from scratch on your phone, which often resolves issues related to error 500121.

If you are an administrator, please first check whether another administrator in your organization can reset your MFA registration using the same procedure above. 

If you are the only administrator in the tenant and cannot access your account, you'll need to contact Microsoft Support directly: Contact Microsoft customer support | Microsoft Support 

In this situation, the Microsoft Data Protection team has tools and processes in place to verify identity and regain access to administrator accounts.   

Here are some tips and an example of a prompt to help you navigate the IVR more effectively:   

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

What kind of problem are you experiencing?          

Answer: Authenticator          

What products do you use?          

Answer: Office 365 for business          

Is this for an education or company account?          

Answer: For companies          

Are you an administrator?          

Answer: Yes          

Are there any other administrators in your organization?          

Answer: No. I am the only admin in my tenant           

Do you need a... Service request?           

Answer: Yes. I need to create a ticket. Please send me direct to the Data Protection Teams.  

During the phone call, you will need to provide the information you have received through your subscription, such as: Your company name, billing information, phone number, alternate email address, etc. Therefore, our privacy team can help you reset your multi-factor authentication, and after the reset, you can add your account back to your authenticator app on your new phone and set it up from scratch or choose a different authentication method to log in to your account.  

If calling support hasn’t been effective so far, there is a workaround you might consider. You can create a new Microsoft 365 tenant by signing up for a trial subscription here: Microsoft 365 Business Plans and Pricing | Microsoft 365    

Once the new tenant is created, you’ll be able to sign in to the Microsoft 365 admin center and submit a support ticket from there. In your request, clearly explain that you need help with regaining access to an administrator account in your original tenant and ask to be routed to the Data Protection team. This approach typically ensures that the ticket is properly assigned and handled by a real support engineer rather than remaining stuck in automated flows or disconnected mid-process.  

Important note: If you use a trial subscription solely for contacting support, remember to cancel it afterward to avoid any unintended charges. 

As this is a user-to-user community support forum, I do not have the ability to make changes directly to your account or service. I can only guide you to the appropriate support channels and resources for further assistance. I sincerely hope these steps help you regain access to your account as quickly as possible.

Thank you for your understanding.

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