Locked Out of Microsoft 365 Global Admin Account Due to MFA (Error 500121) [7 Fixes]

If you’re the only Global Administrator in your Microsoft 365 or Entra ID tenant and suddenly find yourself locked out due to MFA issues. Many admins encounter Error Code 500121, preventing them from logging in or verifying their identity with Microsoft Authenticator.

What Does Error Code 500121 Mean?

Error Code 500121 indicates that authentication failed during the multi-factor authentication (MFA) step. This usually happens when:

• The Microsoft Authenticator app is out of sync or removed.
• The account was accidentally blocked after pressing “Not me” or “Report Fraud.”
• No backup MFA methods (like SMS or phone call) are configured.
• The account is stuck in the “Blocked users” list in Azure AD / Entra ID.

Sample Error:

Error Code: 500121
Request Id: XXXXXXXXXXXXXXXXXXXXXX
Correlation Id: XXXXXXXXXXXXXXXXXX
Timestamp: XXXXXXXXXXXX

If you’re the only Global Administrator, this error means you can’t reset your MFA or create a Temporary Access Pass (TAP) yourself.

Fix 1: Check for Blocked MFA Status (If Another Admin Exists)

If your organization has another Global Admin:

1. Go to Microsoft Entra admin center → Protection → Multifactor authentication → Block/unblock users.
2. Check if your account is listed under Blocked Users.
3. If yes, select your user and click Unblock.
4. Try logging in again and approve the sign-in request.

If you’re the only admin, proceed to the next fix.

Fix 2: Contact Microsoft 365 Support to Reset MFA

When no other admin exists, Microsoft support must intervene.

Steps:

1. Visit the official support portal: https://admin.microsoft.com/support
2. Select Technical Support → Sign-in or MFA issue.
3. Include:
   • Tenant domain (e.g., yourcompany.com)
   • Error code (500121) and timestamps
   • Tenant ID (from billing or Azure portal emails)
   • Proof of ownership (billing email, domain verification, or invoice)
4. Request them to temporarily disable MFA or reset MFA registration for your user.

Once verified, Microsoft will lift MFA enforcement so you can reconfigure your Authenticator.

Fix 3: Use a Backup Sign-In Method (If Configured)

If you previously added a backup MFA method such as:

• A phone call or text message verification,
• A security key, or
• An alternate Authenticator device,

you can select “Use another verification method” during sign-in.
This allows access without the primary app.

Fix 4: Use Domain Ownership Verification to Prove Identity

If you don’t have backup verification methods, Microsoft may request proof of tenant ownership.

Be prepared to provide:

• A DNS TXT record for your domain (Microsoft will give a value to add).
• Billing email and payment information.
• Any previous support case IDs or invoice numbers.

Once ownership is confirmed, support can disable MFA or unlock your account.

Fix 5: Request a Temporary Access Pass (TAP) via Microsoft Support

If your tenant uses Entra ID Protection, ask support to generate a Temporary Access Pass.
This one-time code allows you to:

1. Log in securely without Authenticator.
2. Access My Sign-Ins → Security Info.
3. Register a new Authenticator or alternate MFA method.

Fix 6: Use Microsoft Authenticator Recovery Option (If Previously Synced)

If you had cloud backup enabled in the Authenticator app:

1. Install Microsoft Authenticator on a new phone.
2. Sign in with the same Microsoft account used for the backup.
3. Choose Restore from Backup.
4. Once restored, retry login approval.

If backup was disabled, this option won’t work — move to the next fix.

Fix 7: Prevent Future Lockouts

Once access is restored, follow these best practices:

Bonus: How to Create a Break-Glass Account (Post-Recovery)

A Break-Glass Account is a last-resort admin account that bypasses MFA in case of lockouts or service outages.

Setup Steps (after you regain access):

1. Sign in to Entra Admin Center → Identity → Users → New User.
2. Create a new account (e.g., [email protected]).
3. Assign Global Administrator role.
4. Exclude it from Conditional Access MFA policies.
5. Store the credentials securely (password manager + printed sealed copy).
6. Log in once every 30–60 days to prevent automatic disablement.

Tip: Keep two break-glass accounts in different secure locations for maximum safety.

See also: How to Fix Locked Microsoft Business Account

Being locked out of your Microsoft 365 admin account with MFA error 500121 can bring your operations to a halt — but recovery is possible with identity verification and support escalation.

If you are the only admin, the fastest path is contacting Microsoft Support and requesting temporary MFA disablement or reset after proving ownership.