Error code 500121.

Question

Error code 500121. I am locked out of my Microsoft 365 Developer tenant due to MFA. The original Authenticator device is no longer available. No Global Administrator can sign in. Requesting MFA reset or tenant recovery.

id :[Moderator note: personal info removed]

Answer 1

Please note that our forum is a public platform, and we will modify your question to hide your personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data.

Please note that this is the ko-kr forum. We kindly recommend posting your question in Korean so that more community members can assist you. Alternatively, you may consider posting in the English forum if you prefer to use your native language. We sincerely appreciate your understanding.

Hi @형우 이

Thank you for reaching out to the Microsoft Q&A Forum and sharing your experience.

Based on the information you shared, I understand that you are completely locked out of your Microsoft 365 tenant because the only Global Administrator account is blocked due to an MFA issue.

In this situation, there are two official paths you can take to regain access to the tenant:

1.Please visit the following page and reach out to phone number via: Customer service phone numbers - Microsoft Support

From what I know, you will need to get past the initial AI system to reach the live support team. You can refer to the guide below for tips on how to get through more easily:

2.If method 1 is not working, please follow this link to create a trial tenant: https://www.microsoft.com/en-us/microsoft-365/business/microsoft-365-business-basic?msockid=3eb6980b5c6860e63a588d0c5d1761d6 - 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 "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.

On the other hand, if you do create the trial and it resolves the issue, please remember to cancel the subscription afterward to avoid any related charges. Cancel your Microsoft business subscription in the Microsoft 365 admin center | Microsoft Learn

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

---

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

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.