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A massive global service outage from Microsoft has caused problems or, in some cases, disabled entire services in various regions of the world, including email and artificial intelligence products.
According to monitoring website Downdetector, reports of problems with email provider Outlook peaked globally around 18:00 GMT on Thursday.
Microsoft has claimed that the service outage was not caused by a cybersecurity incident, but efforts to fix the problems have so far not been very successful.
Here's what we know about the affected services and what went wrong.
What services are affected?
Microsoft 365 services - including Teams, Outlook and Microsoft's artificial intelligence software Copilot - have been affected by "connectivity issues".
The full extent of the outage has yet to be confirmed, but monitoring website Downdetector recorded 140,000 users from 74 countries reporting problems with Outlook on Thursday night.
According to Microsoft's website, more than 430 million people use Microsoft 365 applications.
This software is also used by companies around the world and is expected to have a knock-on effect on other services.
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While customers report varying levels of access, many have been unable to send or receive email, or view certain files or details in their calendar apps.
Some users have been able to use Teams normally and are using the messaging and online meeting features as usual.
What other companies and institutions have been harmed?
Tech giants OpenAI and Anthropic have reported problems as a result of the service interruption.
OpenAI, the company that created ChatGPT, has stated that it is investigating an issue affecting its connections to Microsoft services, which has caused some tools to not work as expected.
Government agencies and services, including the Singapore government and Australia's intelligence agency, have also claimed to have been affected.
Several primary care health centers across the UK have warned of potential problems, with some telling patients to make urgent queries by phone rather than by email or web form.
What went wrong?
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Microsoft has ruled out a cyberattack and attributed the service interruption to a "high load" on its infrastructure.
The term refers to the situation in which the servers support a much larger volume of load than usual.
In the case of the Microsoft outage, a large number of servers were left "unexpectedly inaccessible," the company reported, generating additional traffic on the remaining servers, overloading them.
On Friday morning, Microsoft said it had seen "minor success" in its efforts to fix the incident.
The company indicated in its latest update that it continues to monitor activity in all regions to evaluate the status of servers and determine what actions it can take to improve capacity.
In a previous statement, the tech giant had said that its attempts to fix the problem were "not yielding the expected results."
What have the experts said?
Australian cybersecurity expert Troy Hunt told the BBC that the outage could have far-reaching consequences.
"Microsoft is a fundamental part of the Internet's infrastructure and reminds us how crucial email remains."
"This disruption not only affects many people's ability to work, but also things like communication to make appointments, purchase items that require verification, create or access accounts and services," he said.
Paul Spain, from the New Zealand consulting firm Gorilla Technology, stated that, with emails and services out of service, companies have practically "lost a working day", which is "frustrating" for users.
This article was originally written in English and we used an artificial intelligence tool to translate it. A BBC journalist reviewed the text before publication. Learn more about how we use AI.
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