Security News > 2021 > September > Microsoft 365 MFA outage locks users out of their accounts
Microsoft is investigating an ongoing Multi-Factor Authentication issue preventing some customers from logging into their Microsoft 365 accounts.
"We're investigating an issue with Multi-Factor Authentication that is preventing some users from accessing Microsoft 365 services. Additional information will be provided in the admin center under MO287933, the company tweeted."
According to the company, only on-premises users are impacted by this Microsoft 365 MFA issue, with no cloud customers being affected.
"This issue could potentially affect any user if they leverage MFA and either Network Policy Server or Active Directory Federation Services to access Microsoft 365 services. This issue only affect on-premises users, and cloud hosted users are not affected."
Another large-scale outage in March knocked down multiple Microsoft services one month earlier, including Microsoft 365, Microsoft Teams, Exchange Online, Forms, Xbox Live, and Yammer following widespread Azure Active Directory login issues.
In September 2020, Microsoft customers experienced another worldwide outage showing "Transient" errors which also knocked down Office 365 and related services, including Microsoft Teams, Office.com, Power Platform, and Dynamics365.