Overview

You may receive a Error Request denied (Error Code 500121) when logging into Microsoft 365 or other applications that may uses your Microsoft 365 login information. 

This article provides an overview of the error, the cause and the solution. 

Error

Clicking on View details shows Error Code: 500121

Cause

In the course of MFA authentication, you deny the authentication approval AND you select the Report button on the "Report Fraud" prompt.

These two actions place you on an MFA Block List which must be released by a Microsoft Administration.  

Solution

1. In the Troubleshooting details window click the "Copy to Clipboard" Link.
2. Using this link to report the issue: Report MFA Issue 
3. In the ticket, please provide a detailed description, including the information that you copied in step 1