Microsoft suffered a global outage that disrupted businesses and government agencies in more than 70 countries after a glitch in its network knocked Exchange Online offline, SiliconANGLE reported. The fault surfaced at about 12:35 p.m. EST on Thursday, and the company had still not fully restored its infrastructure when the report was published. Microsoft later said it was "deeply sorry" for the disruption, which lasted almost 24 hours before services broadly recovered, according to BBC News.
The incident centred on Exchange Online, the cloud service organisations use to store employees' inboxes and calendars. On-premises deployments of Exchange Server were not affected, SiliconANGLE reported, but the outage disrupted Microsoft Teams and Microsoft Copilot 365 features that rely on data from users' Exchange inboxes, and Intune, the tool administrators use to manage employee devices, also experienced technical issues.
What Went Wrong
Microsoft's first explanation, reported by SiliconANGLE, was that the incident "was introduced by an issue during an earlier network capacity upgrade that surfaced following a recent network change". The company said it had addressed the underlying issue and was restoring service to remaining customers and regions. It added that the outage was not caused by a cyberattack or by artificial intelligence agents, a point BBC News also reported. The Register put the start of the incident at 1826 GMT on November 12, noting that Exchange Online fell over, viewing recently used files in the Microsoft 365 application became problematic and Copilot "threw a wobbly". Microsoft 365 Education was affected too. At 1401 GMT on November 13, Microsoft reported that it was "continuing to see improvements in service availability". Recovery was gradual. SiliconANGLE reported that Microsoft published an update at 2:30 a.m. saying it was seeing "positive results" after patching an "upstream authentication/routing configuration" module, and that systems in the Asia Pacific region began regaining service access about three hours later, with North America and Europe following shortly after. BBC News reported that by 13:32 the company cited "broader improvements" in North America, "sustained improvements" across much of Europe and "encouraging recovery signals" in the Asia Pacific region. Microsoft said it restored services gradually because of the scale of the problem and to help ensure stability once services were running again, and that it had no estimated time for full recovery.Who Was Affected
The commercial reach was broad. SiliconANGLE reported that electric vehicle maker Workhorse Group pushed back its earnings call from Thursday to Monday, while shipping giant Maersk and stock exchange operator Euronext notified customers of communications issues. Several US municipalities reported technical problems and a number of court cases were delayed. In the UK, the National Pharmacy Association warned that the outage might slow prescription processing, and hospitals, public transport agencies and schools were affected. BBC News added detail across regions. The Japanese government, the Philippines Supreme Court and the Australian spy agency were affected, as were trains, hospitals and courts in North America. In the UK, some parts of the NHS, including GPs and hospitals, were affected, along with some schools and police forces. UK cyber minister Liz Lloyd said the incident had "limited" impact on critical frontline services such as 999 calls and that there had been no disruption to the transport network. In Canada, the national rail network said passengers might not receive email updates about their trips, and hospitals across the country had email issues. In the US, staff members from the House of Representatives told Politico the outage had set back an entire day of legislative work. Singapore's government acknowledged some systems were impacted, and in Turkey, advisers and officials attending the COP31 climate summit in Antalya were unable to access Outlook. The effects reached small businesses and individuals as well. Peter Pentz, a winemaker in South Africa, told BBC News his entire business was basically brought to a "standstill", with communication to exports halted and "critical production work" stopped. Georgia from Staffordshire said the outage had delayed her first house purchase after an eight-month wait, because her solicitor could not contact other agencies.The Dependence Question
The outage handed critics of single-vendor dependence an unwelcome case study. Jos Poortvliet, co-founder of Nextcloud, told The Register: "This incident shows how dependent organizations are on a single ecosystem. Especially in critical infrastructure, monopolies are increasing the risk of stalling businesses globally if an incident occurs." Civo chief executive Mark Boost told the same publication: "The real concern isn't that Microsoft has suffered an outage. It's that we've allowed so much of our critical infrastructure to become concentrated in the hands of so few companies, creating enormous single points of failure." Dame Chi Onwurah, chair of the Commons Science and Technology Committee, said the outage "only serves to highlight once again the lack of resilience in the UK's digital infrastructure, and the dangers that this dependency can pose to our security, economy and public services", The Register reported. BBC News cited Rob Demain, chief executive of cybersecurity firm e2e-assure, who called the event a "stark reminder" of how heavily organisations rely on a handful of big tech providers, and Matt Saunders of Adaptavist, who said it would be challenging to mitigate against a similar problem because "it's almost impossible for a business to function without tools such as Microsoft". Scale explains part of the exposure. BBC News reported that more than 430 million people use the affected products worldwide. The Register noted that Microsoft this week warned users to treat its unsupported Exchange Server 2016 and 2019 as "permanently vulnerable", while moving to Exchange Online brings its own dependencies.Commercial Impact
For operators, the immediate questions are contractual and operational. Microsoft has said a full post-incident report will be released once its review is complete, and SiliconANGLE reported that a detailed technical report is planned once all services are fully restored. The Register observed that beyond any compensation claims, Microsoft may face awkward conversations about dependencies when contracts come up for renewal. The company said it was monitoring the backlog of emails that piled up while the service was offline to ensure no data loss occurs, according to SiliconANGLE. The disruption also had a direct commercial cost for some customers. Workhorse Group's decision to move its earnings call, reported by SiliconANGLE, is a reminder that scheduled market events can be derailed by a supplier's infrastructure fault. For smaller firms, the impact was more immediate: Pentz's winery lost export communication and critical production work, as BBC News reported.Risks and Unknowns
The cause is characterised by Microsoft as a configuration issue tied to a network capacity upgrade, not an attack, but the full technical account is still pending. The company has not given a timeline for complete restoration, and the residual backlog and any downstream effects on dependent products remain to be confirmed. The outage also illustrates a structural risk that individual customers cannot easily resolve: as Saunders noted, running a genuine second service in parallel is difficult in practice.Why It Matters
The Microsoft global outage shows how a single configuration fault at one cloud vendor can cascade into courts, hospitals, government systems and corporate communications across more than 70 countries within a day. For operators, the practical lesson is that resilience is not only a technical question but a contractual and procurement one, and that the concentration of critical infrastructure in a small number of providers is a structural exposure that individual customers cannot easily resolve.FY Outlook
Microsoft has said it will publish a full post-incident report once its review is complete, and SiliconANGLE reported that a detailed technical report is planned once all services are fully restored. The Register noted that Microsoft may face awkward conversations about dependencies when contracts come up for renewal. The next substantive checkpoints are the technical report, confirmation that the email backlog has been cleared without data loss, and any contractual or regulatory follow-up in the UK and elsewhere.Sources and References
- SiliconANGLE (siliconangle.com)
- BBC News (bbc.co.uk)
- The Register (theregister.com)
