Hourslong Microsoft outage disrupts Korean companies' daily operations

A global Microsoft outage disrupted operations at major Korean companies on Friday, leaving some employees unable to access emails, coordinate with business partners and manage daily workflows as the tech giant struggled to restore its systems.

The disruption affected multiple Microsoft services, including its Outlook email, parts of its Teams messaging app, Microsoft 365 productivity tools and Copilot artificial intelligence (AI) assistant.

While the impact varied by company depending on the services used, some employees were forced to postpone work or turn to alternative communication channels.

Some major companies sent urgent companywide notices alerting employees about the outage and asking them to check which Microsoft services were affected. Some companies also circulated email notices identifying services that were unavailable.

An information technology (IT) industry official said employees had turned to other messaging apps to keep some work moving but the workaround offered only limited relief.

“Since we cannot use email, we are exchanging files through messaging apps. But some files cannot be sent that way, so certain tasks are on hold,” the official said.

“We also cannot access shared calendars linked to employees’ schedules, which is inconvenient. For now, we’re focusing on tasks we can work on with the materials available.”

The disruption was particularly severe for businesses that rely on Microsoft's cloud-based collaboration tools.

A retail industry official said the disruption left her team struggling to communicate with suppliers and coordinate work across departments, as email services and Microsoft's document management platform SharePoint became inaccessible.

"We need to communicate with our business partners, but we cannot even check the emails we've received from them or who sent what. And even if I send an email through personal mail, if they use Outlook, they can’t check it at all," the official said.

"Shared spreadsheets used to compile work across the company are also managed through SharePoint on Microsoft 365, and those services are down as well, making it extremely difficult to work."

An official of a major business group said the outage had called into question Microsoft's reputation as a global IT giant and market leader.

"As a company that prides itself on driving workplace productivity and efficiency, Microsoft should feel a greater sense of responsibility for leaving businesses and users around the world struggling with disruptions throughout the day due to flaws in its own quality and service management systems," the official said.

Beyond questions of corporate responsibility, the outage could also expose Microsoft to potential compensation claims from affected businesses.

"From a legal standpoint, a claim is certainly possible in theory. Even if there was no intent, negligence could still be established," said Lee Joo-heon, an attorney at law firm Songyul.

However, he noted the challenge would be proving that the disruption caused measurable financial losses and determining how much compensation could be sought.

"In Korea, damages are generally awarded in monetary form, so the amount of loss ultimately has to be calculated (financially)," Lee said. "For large companies, daily revenue does not necessarily decline simply because their operations are disrupted. The key will be determining how much damage they suffered over the hours they were affected."

Asked whether Microsoft had compensation arrangements for affected customers, Microsoft Korea said the local office had not received any related information from its headquarters.

"We have not received any information from our headquarters regarding compensation, so we have nothing further to share at this point," its official said.

Downdetector, which tracks online service disruptions based on user reports, recorded over 138,000 reports of Outlook problems in the United States at its peak shortly after 1 p.m. on Thursday (local time).

It said reports also surged in the United Kingdom, India and New Zealand, with nearly three in 10 reports coming from outside the U.S. during the first two hours of the disruption, as the outage spread to 74 countries and territories within roughly an hour of reports beginning to climb in the U.S.

Microsoft said the outage was caused by some servers unexpectedly going offline, putting additional strain on the rest of its infrastructure, rather than by a surge in traffic and said it had found no evidence of a cyberattack.

“We regret that today’s outages caused disruptions for our customers, and we are working to address the issue,” Charles Lamanna, Microsoft's executive vice president of Copilot, Agents and Platform, wrote on social media. “For now, I can confirm that there is no indication this is the result of malicious or cyber activity.

The company said it was redistributing traffic across its global infrastructure and bringing affected servers back online to restore capacity. However, its initial recovery measures did not work as expected, prompting the company to explore alternative ways to increase capacity and address traffic imbalances.

“We’ve monitored the status of the changes applied to improve serviceability and confirmed they're not taking as expected,” Microsoft said. “We’re identifying alternate workstreams that can be applied to increase capacity in the face of sustained traffic management imbalances.”

The outage also disrupted integrations connecting OpenAI's and Anthropic's AI services to Microsoft's workplace tools, potentially limiting their ability to retrieve and work with business data.

OpenAI said new connections through its Microsoft connectors could fail and that some tools were not working as expected.

Anthropic reported failures affecting its Microsoft 365 connector, including access to email, SharePoint files, Teams chats and calendars, as well as difficulties establishing new connections.