Lost access to my Microsoft 365 Developer admin account (MFA issue - error 399287)

Question

Lost access to my Microsoft 365 Developer admin account (MFA issue - error 399287)

Phong Phong 0

Dear Microsoft Developer Support Team,

I’m reaching out for assistance with my Microsoft 365 Developer tenant.

I have lost access to my global admin account after changing my password.

When I try to sign in, the system requires multi-factor authentication (Microsoft Authenticator or SMS).

However, my Authenticator app on my mobile device cannot log in due to the password change, and when I attempt to verify via phone number, it shows the error code 399287.

[Removed PII]

Issue: Unable to complete MFA verification or access the tenant admin portal after password reset.

I kindly request your help to remove or reset the MFA requirement for my admin account, or alternatively provide temporary admin access so I can recover and manage my tenant.

Thank you very much for your time and support.

Please let me know if any additional information is required to verify my ownership.

Best regards,

2 answers

Your answer

Answer 1

Jade-T 6,835 Microsoft External Staff Moderator

Hi @Phong Phong

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

I understand that you are currently unable to access your Microsoft 365 Developer tenant because your Authenticator app and phone verification are not working after a password change. This issue is caused by an MFA verification error (code 399287).

Since the system cannot complete verification, you will not be able to restore access on your own. For security reasons, only Microsoft Support can verify your identity and help you regain access to your tenant.

To move forward, you can use one of the following support channels:

1. Call Microsoft Support

You can find the support number for your country or region here: Customer service phone numbers - Microsoft Support

When speaking with the support agent, explain that your Global Admin account is locked due to MFA verification failure.
Provide your tenant details, global admin account, error code 399287, Request ID, Correlation ID, and timestamp. Ask for assistance to reset MFA or temporarily regain admin access.

2. Use a New Trial Tenant

If phone support is not an option, you can create a free Microsoft 365 trial tenant: Free Trial - Try Microsoft 365 for a month

Sign in to the trial tenant’s Admin Center and submit a support request. In the request, mention that you are contacting on behalf of your locked tenant.
Be prepared to verify domain ownership if requested (e.g., by adding a DNS TXT record).

Once Microsoft verifies your identity and ownership, they will assist you in regaining access to your admin account.

I hope these steps help you recover access quickly. Please let us know if you need any further assistance.

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.

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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Phong Phong 0 Reputation points

2025-10-21T03:30:35.9333333+00:00

Hi Jade,

I have already called Microsoft Support, but the AI-based support system doesn’t seem to understand the actual issue I’m facing.

My problem is related to MFA verification failure (error code 399287). Both my Authenticator app and SMS verification no longer work, which prevents me from accessing my Microsoft 365 Developer tenant.

Please help restore the trust status of my phone number or alternatively provide verification support via my registered email: [removed PII].

I would really appreciate your help in re-enabling my access or resetting MFA verification for my account.

Thank you very much for your time and support.
Jade-T 6,835 Reputation points Microsoft External Staff Moderator

2025-10-21T04:02:51.4933333+00:00

Hi @Phong Phong

I understand how frustrating this must be. Since this is a public forum, please note that I’m a moderator here and don’t have access to your tenant or the ability to reset MFA. In cases like this, what we can do is guide you toward the correct support path.

If you’ve already tried calling Microsoft Support but only reached the automated system, the best workaround is to create a new Microsoft 365 Business Standard trial tenant using this link: Microsoft 365 Business Standard.

You’ll need to use a new email address (not your old or personal one) to sign up. Once the tenant is ready, go to Admin Center > Support > New service request and explain that you lost MFA access after resetting your password and need to restore your original account.

Submitting a ticket from inside a tenant ensures your case is routed to a live support engineer instead of the automated phone system. This process is necessary because only Microsoft Support has the tools to remove MFA when the self‑service options fail.

When calling Microsoft Support again, speak clearly and say: “Personal Microsoft account”, “Microsoft 365 Developer Program E5”, “locked out due to Authenticator app”.

If asked for product/account type, answer “Microsoft 365 Developer Program / personal account”. Emphasize that you cannot complete MFA and need to be connected with a human agent.

Have your proof of ownership ready (registered email, subscription details, or domain verification) so the support team can validate your account quickly. This approach usually helps you get past the AI system and connect with a real support agent.
Phong Phong 0 Reputation points

2025-10-21T04:18:29.1266667+00:00

Hi @Jade-T ,

Thank you for your guidance. I have already tried contacting Microsoft Support, but the automated system didn’t connect me to a human agent who could handle my issue.

My Microsoft 365 Developer account is still locked due to an MFA verification failure (error code 399287). Both my Authenticator app and SMS verification are not working, so I cannot complete the sign-in process.

Could you please reach out to the engineering team to unblock MFA for my account from the backend, or remove the bad reputation associated with my phone number, as you mentioned in other similar cases?

My registered email address is [removed PII].

I would appreciate it if you could help restore the trust status of my phone number or enable alternative verification via email.

Thank you so much for your support and understanding.
Jade-T 6,835 Reputation points Microsoft External Staff Moderator

2025-10-21T04:48:11.4366667+00:00

Hi @Phong Phong

I understand how difficult and frustrating this situation must be for you.

Just to clarify, I’m a moderator here on the public forum, not part of Microsoft Support. As a moderator, I don’t have the permissions to take actions like contacting Support or creating a tenant on your behalf. These steps need to be done directly by you, because the support team must carefully verify your account details - something moderators cannot do since we don’t have access to your tenant or personal information. I’m sorry I can’t handle this part for you but following that process will connect you with the right support engineer.

If you still can’t get through to a live agent, the next step and effective way forward is to create a new Microsoft 365 trial tenant and submit a service request from there, as I’ve already outlined. This process is necessary because it ensures your case is routed to a real support engineer who has the proper tools to reset MFA.

Also, please remember this is a public forum, for your own privacy and security, please don’t post sensitive information such as your personal email address here.

I know it’s not the easiest path, but it’s the one that will actually get you connected with the right support engineer who can reset MFA. Thanks for your understanding. I hope this clears up what I can and cannot do from my side.
Phong Phong 0 Reputation points

2025-10-21T05:05:46.46+00:00

Hi @Jade-T ,

Thank you for your clarification and for taking the time to explain the process.

I fully understand that moderators here do not have access to user tenants or permissions to contact Support on behalf of others. However, I’m currently unable to create a new Microsoft 365 trial tenant due to account restrictions, and I’d like to know if there is any alternative way to verify my ownership and reset MFA without creating a new tenant.

I’ve already attempted to contact Microsoft Support, but the automated system did not connect me to a live agent. Could you please advise on the exact steps or contact form that allows me to reach a real support engineer who can assist with MFA recovery?

I’m ready to provide any required verification details privately through secure channels if necessary.

Thank you again for your understanding and for pointing me in the right direction.

Best regards
Jade-T 6,835 Reputation points Microsoft External Staff Moderator

2025-10-21T05:21:53.8866667+00:00
Hi @Phong Phong

I understand how stressful it can be to feel locked out of your account, especially when your work or access depends on it.

At this time, the forum doesn’t have another contact form or process to offer, only Microsoft Support can securely verify your identity and reset MFA. When you call Support, try speaking slowly and clearly, and use phrases such as:

“Personal Microsoft account”

“Microsoft 365 Developer Program E5”

“Locked out due to Authenticator app”

If asked about product/account type, you can answer: “Microsoft 365 Developer Program / personal account”. It may also help to emphasize that you cannot complete MFA and need to be connected with a human agent.

If the system doesn’t connect you right away, repeating these keywords or even saying “representative” or “human support” sometimes helps the automated system route you to a person, though it may take a few tries. It is the secure path that ensures your case reaches a support engineer who can assist with MFA recovery.

I truly hope you’ll be able to regain access soon.
Phong Phong 0 Reputation points

2025-10-21T09:07:05.8466667+00:00

Hi @Jade-T ;

Thank you for your explanation.

I understand that calling Microsoft Support is the main way to reset MFA. However, could you please let me know if there is any other possible way to contact Microsoft Support — for example, by email, web form, or live chat — since phone support is quite difficult for me to access right now?

I really appreciate your help and guidance.

Best regards
Jade-T 6,835 Reputation points Microsoft External Staff Moderator

2025-10-22T01:22:08.0433333+00:00

Hi @Phong Phong

For MFA recovery and access to a locked Global Admin account, there aren’t public channels such as email, web forms, or live chat that can bypass security verification. These actions are sensitive and require trusted, real-time identity verification.

Microsoft Support is the official channel that can securely verify your identity and reset MFA. This process may involve Microsoft’s Data Protection and Security teams to ensure compliance and to protect tenant data. They can perform additional checks, such as confirming Request/Correlation IDs or domain ownership, and use internal tools that are not accessible through public channels.

The most practical way to regain access, as mentioned above, is to follow the official steps: contacting Support directly or submitting a request from a Microsoft 365 trial tenant, which tends to be the most effective approach.

I hope this helps clarify the available options from this forum. I also understand how concerning it can be to lose access to such an important account, and I truly appreciate your patience and understanding while working through the recovery process.

Answer 2

Hi Jade,

I have already called Microsoft Support, but the AI-based support system doesn’t seem to understand the actual issue I’m facing.

My problem is related to MFA verification failure (error code 399287). Both my Authenticator app and SMS verification no longer work, which prevents me from accessing my Microsoft 365 tenant.

Please help restore the trust status of my phone number or alternatively provide verification support via my registered email: [removed PII].

I would really appreciate your help in re-enabling my access or resetting MFA verification for my account.

Thank you very much for your time and support.

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Lost access to my Microsoft 365 Developer admin account (MFA issue - error 399287)

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