How to Fix Microsoft Authenticator Error 500121 After Denying a Request
Question details
The user is attempting to restore Microsoft Authenticator functionality after receiving error 500121 and no longer receiving approval notifications.
- Product
- Microsoft Authenticator
- Device & OS
- not provided
- Scenario
- Trying to sign into an account after previously clicking 'I do not recognize this request' on an MFA prompt.
- Observed behavior
- The sign-in request is automatically denied with Error 500121, and new multi-factor authentication (MFA) approval notifications fail to reach the user's phone.
Verify if you have alternate authentication methods enabled for your account, such as SMS or a secondary email, which may allow you to bypass the blocked Authenticator app temporarily.
Contact Microsoft Authentication Support Specialists
Because Error 500121 involves Microsoft Entra ID backend security blocks, escalating the issue to specialized Microsoft engineers is the most effective resolution.
When you select 'I do not recognize this request,' the system flags your account to prevent potential unauthorized access. Unblocking this typically requires backend intervention that standard support channels cannot provide.
Navigate to the Microsoft Authentication App Community at learn.microsoft.com/en-us/answers/products/azure?product=identity.
Click the 'Ask a question' button. If you are locked out of your primary account, sign in using a secondary or personal Microsoft account.
Create a new post including the specific error code (500121), your account type (business, school, or personal), and explain that the error started after denying a previous prompt.
Request an MFA Reset from Your IT Administrator
If the affected account is managed by a business or school, the organization's IT administrator can manually reset your MFA settings.
Stay Productive Offline with WPS Office
If Microsoft Authenticator Error 500121 is locking you out of your Microsoft 365 cloud environment, you can still meet your deadlines. WPS Office offers a powerful, offline-capable productivity suite that doesn't require complex cloud authentication to view or edit your documents.
- 1. Download the Software: Visit the WPS Office website and download the free installation package for your operating system.
- 2. Install Locally: Run the installer. The process takes only a few minutes and does not require complex IT provisioning.
- 3. Open Your Files Offline: Launch WPS Office to immediately open, edit, and save your existing .docx, .xlsx, and .pptx files directly on your local drive.
Frequently Asked Questions
What causes Microsoft Authenticator Error 500121?
Error 500121 occurs when authentication fails during a multi-factor authentication (MFA) request. This often happens because the system's security protocols blocked the request after a previous prompt was marked as suspicious or manually denied by the user.
Why did my phone stop receiving MFA push notifications?
When you tap 'I do not recognize this request,' Microsoft Entra ID assumes your credentials may have been compromised. To protect your account, it stops sending approval notifications to the app until the security block is cleared by an administrator or Microsoft support.
Can I fix Error 500121 without an administrator?
Generally, no. If you are an end-user in a corporate or educational environment, only an IT administrator can reset your MFA status. If it is a personal account, you must contact Microsoft Support through their community forums to lift the restriction.
