WORLDTECHMicrosoft restores Microsoft 365 after 24-hour outage, blames network upgrade
Microsoft has restored Microsoft 365 services after a global outage that disrupted Outlook, Teams and other applications for more than 24 hours. The company says the cause was a technical fault tied to a network capacity upgrade, not a cyberattack.
Outage began with mailbox access problems
The disruption began on Thursday and affected access to Exchange Online mailboxes, along with features linked to Outlook, Teams and Microsoft Copilot.
On Saturday, Microsoft said it had restored service to the remaining affected customers and regions. Customers were directed to incident MO1550821 in the Microsoft 365 admin center for updates.
Network upgrade identified as root cause
On Friday, Microsoft said the outage stemmed from a problem introduced during an earlier network capacity upgrade, which emerged after a recent network change.
The company stated that the problem was a technical issue unrelated to cyber threats or AI agents, which are software systems that carry out multi-step tasks rather than answering a single question.
Microsoft said it had addressed the underlying issue and brought services back gradually, checking stability at each stage before moving on.
Government and AI services hit
Government agencies in Japan, Singapore and the United States reported email problems during the outage. Connections between Microsoft 365 and AI assistants were also affected.
OpenAI said the Microsoft 365 connector in ChatGPT was operating normally again. Anthropic marked its Microsoft 365 connector and Claude for Outlook incident as resolved.
Microsoft apologises and promises review
Microsoft apologised for the disruption and said it will publish a full post-incident report once its review is complete.
Open questions
- What exactly was the fault introduced during the network capacity upgrade?
- When will Microsoft publish its full post-incident report?