September 29, 2021

Microsoft was investigating the now solved Multi-Factor Authentication (MFA) issue that occurred late Tuesday and prevented some users from logging into their Microsoft 365 accounts.

According to the tech giant, only customers using on-premises MFA servers were affected, with Cloud Authentication remaining unaffected.

“We’ve identified 503 errors from specific processing components, and we’re reviewing these errors to identify the source,” Microsoft posted in its admin center.

After a few hours, a new update to the MO287933 admin center tracking ticket, Microsoft posted that it had fixed the issue for some affected users.

“In parallel, we continue to investigate the underlying root cause so further actions can be taken to ensure the issue does not reoccur. Engineering remains engaged to ensure that the service remains in a healthy state,” the tech giant said.

For more information, read the original story in Bleeping Computer.