problem with admin

Question

Hello,

I am the only Global Administrator of our Microsoft 365 tenant and I am locked out due to MFA. I receive Error Code 500121 and cannot access the Microsoft 365 Admin Center or Security Info.

I need assistance with Tenant Access Recovery and an MFA reset.

Error Code: 500121 Request ID: [Moderator note: Personally Identifiable Information removed] Correlation ID: [Moderator note: Personally Identifiable Information removed] Timestamp: 2026-07-16T08:41:57Z

Thank you.

Answer 1

I noticed that you posted your question in English, so I’ll respond in English to make sure the explanation is clear and easy to follow. If you’d prefer a reply in a different language, please let me know. 

Please note that this forum is a community support space, so I don’t have the ability to access tenant data or perform actions such as resetting MFA/security information directly. I can only guide you based on documented processes and experience, but I will do my best to point you in the right direction so this can be resolved properly.

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Dear @Mehdi Javadi,

I hope you’re having a good day.

Error 500121 indicates that the sign-in process is failing during MFA verification, if there is only one administrator account in the tenant and you uninstalled Microsoft Authenticator without having another verification method, this is considered an administrator lockout scenario.

In that case, the only supported way forward is to contact Microsoft Support and request a tenant admin recovery / MFA reset. This request is handled by the Microsoft Data Protection / Identity team, who can verify ownership and unblock or reset the MFA configuration for your account.

Please try to find the related hotline number to call the frontline let them raise a ticket for you: Customer service phone numbers - Microsoft Support 

If you choose to contact Microsoft Business Support by phone, you may first be connected to an automated system before contacting a support professional. Based on similar cases of administrator lockouts, the conversation can go something like this:

Automated system: Are you calling as a private individual or a business customer?

You: Business customer.

Automated system: What do you need help with today?

You: Authentication problem.

Automated system: Which Microsoft product or service is affected?

You: Microsoft 365 for business.

Automated system: Can't sign in to the Microsoft 365 Admin Center?

You: Yes.

Automated system: Do you have another administrator in your organization?

You: No, I'm the only administrator.

Automated system: Are you a global administrator for the affected tenant?

You: Yes.

Automated system: Are you calling about an existing support case, or would you like to create a new one? You: I need to create a new support case.

In many cases, the automated system will then indicate that it can connect you with a support representative who can help create a support request and forward the case to the appropriate recovery team.

I would also recommend calling during opening hours when possible. From my experience, it can be difficult to reach the right support queue at times, and automated systems don't always behave as expected. If you can't get through on the first try, consider trying again later or at a different time of day.

If your organization’s Office 365 Business subscription was purchased through a partner or reseller, and you’re unable to open a service request directly, you may also contact the reseller’s support provider and ask them to open a support request on your behalf.

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Alternatively, you can try set up a new trial tenant and submit your support request, please follow this link to create a trial tenant: Compare Office 365 Enterprise Pricing and Plans | Microsoft 365 - after that you will be able to access to Microsoft 365 Admin Center to raise the ticket

Assuming that you have already created an account after registering a free trial and you can go to Microsoft 365 admin center and click Support > Help & support icon to raise your ticket. The agent will be able to create a ticket for you under the affected tenant and then transfer this ticket to Data Protection team who could help you to regain access.

Please mention that you are raising ticket on behalf of the affected tenant that you do not have access to. The support team will help you to create ticket on the affected tenant then later on the Microsoft Data Protection team will assist you.

Note: This process will take more time than usual (7-14 working days) for your account to get access again as Data Protection is always overwhelmed with the number of tickets. As I am forum moderator, I do not have access to Microsoft internal system to assist or push this process to be quicker.

If you do create the trial and it resolves the issue, please remember to cancel the subscription afterward to avoid any related charges. 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.   

I hope my information is helpful. Please give me any updates once you get this resolved.

Warm regards, 

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