Source: Sharecast
The outage, which began around 1800 GMT on Thursday and has continued into Friday, means users are currently unable to send or receive emails through Outlook, with Teams, AI-assistant Copilot and other Microsoft 365 services also affected.
Initially affecting mainly users in the US, the outage went on to cause disruption across Asia-Pacific overnight before Europe was hit as the working day got underway.
Several UK police forces urged people not report crimes online due to the outage, while schools across the country were unable to communicate with parents over email. NHS services were also affected, with problems involving patient referrals and issuing prescriptions.
According to Bloomberg, the disruption also affected financial institutions, with some traders encountering difficulties accessing email-dependent systems and confirming transactions.
Luke Pollard, minister for defence readiness, confirmed to the BBC that government engineers were working with Microsoft.
Microsoft said it was working on a fix. In its latest update on Friday morning, the US tech giant confirmed it was "seeing positive results" for service stability and increased capacity, and that it would "continue to monitor its progress and are working to expand it to servers supporting active regions coming online". It had previously acknowledged that the fix was "not taking as expected".
Microsoft’s executive vice president of Copilot, agents and platform, Charles Lamanna, posted overnight on X that there was "no indication this is the result of a malicious or cyber activity".
The company later reiterated: "As of now, we are not aware of any malicious activity that is causing this incident. We will continue to treat the incident with urgency and priority until full resolution. Once mitigated, we will provide full details of the root cause."
Problems involving server authentication and routing systems were blamed on the disruption, with efforts to restore connectivity initially hampered by servers becoming unresponsive as traffic returned. A subsequent patch appeared to be improving stability, according to media reports, although the company had yet to establish a definitive root cause.
Microsoft shares were down around 1.2% in premarket trading on Wall Street as markets weighed the potential repercussions of the prolonged disruption.
Reporting by Abigail Townsend and Benjamin Chiou