On Saturday night, Microsoft 365 experienced significant service disruptions affecting thousands of users globally. The outages primarily impacted Outlook, Exchange Online, Microsoft Teams, and several other applications, leaving many users frustrated and unable to access their emails and calendar entries.
According to incident reports from the Microsoft 365 admin center, issues began to surface at approximately 8:40 PM UTC. By around 4 PM Eastern Standard Time (EST) on Saturday, Downdetector — which tracks online service disruptions — reported a peak of over 37,000 outage complaints. Users from prominent cities such as London and Manchester expectedly felt the brunt of the disruptions. Many took to social media platform X (formerly Twitter) to voice their frustrations. "So I'm guessing Microsoft Outlook is having issues; everyone around me has just been logged out of their emails," one user noted.
Many users who were logged out were left scrambling for solutions. While some were notable exceptions, with access still available via web interfaces and Android apps, others faced complete inability to log back in. Microsoft, sensing the urgency, asserted, "We're investigating an issue where users may be unable to access Outlook features and services,” giving insight to their troubleshooting approach.
After identifying the problem, Microsoft moved swiftly, posting updates on X detailing their actions. "A recent update to Microsoft 365 authentication systems contained a code issue, resulting in impact to some Microsoft 365 apps and services," the tech giant disclosed. To remedy the issue, they reverted the faulty coding change, which they attributed as the preliminary root cause of the outages.
Following this action, engagement statistics showed signs of recovery. "Following our reversion of the problematic code change, we’ve monitored service telemetry and worked with previously impacted customers to confirm service is restored," Microsoft announced. Nevertheless, some issues persisted. Specifically, Exchange Online users on iOS devices continued facing hurdles, unable to access their calendar or mail messages through the default mail app.
To assist users still affected by these complications, Microsoft suggested some troubleshooting methods through their admin center. "Users may be able to click 'continue' when prompted and navigate back to re-entering their password to attempt to resolve impact," the company explained. These alternative solutions provided necessary hope for users still facing issues.
The service disruptions come among recurrent complaints and technical struggles Microsoft has faced recently. Many users recalled other incidents, like the downtime related to Azure services due to networking issues earlier this year. This downtime heat map confirmed the sporadic access problems for Exchange Online on January 8-10, 2025, causing immense customer strife.
Despite the challenges, users appeared to be regaining access as the evening wore on Saturday and progressed to Sunday. Post-incident communication from Microsoft affirmed, "Our telemetry indicates majority of impacted services are recovering following our change. We'll keep monitoring until impact has been resolved for all services.” This assurance could not have come soon enough for many users who had been without access earlier.
Looking to the future, Microsoft has committed to thoroughly review its change management process to identify ways to prevent the buggy code from slipping through pre-launch testing again. This commitment is part of the broader organizational efforts to improve the reliability of their services, as the company also gears up for the closure of Skype, announcing its transition entirely to Microsoft Teams for communication needs.
With past outages still fresh on users’ minds — including losses suffered during the November and February outages, precisely affecting Microsoft's emails and Teams services — questions about Microsoft’s resilience and its ability to cope with substantial demand loomed large. The company aims to address systemic issues to ascertain they do not resurface.
Microsoft’s service recovery efforts stand as timely reminders of the need for vigilance and proactive management within digital service platforms, especially as they expand and evolve to cope with increasing global demand. It remains to be seen how well they can maintain and secure service integrity for their massive base of users lined up for services globally.