UPDATED with latest company comments: Microsoft is continuing to investigate widespread outages affecting Outlook email and other services offered through its 365 platform.

The tech giant issued a string of social media posts Thursday acknowledging that users had been reporting issues with access, throwing a major wrench into business communications across sectors. Enterprise and business customers of Microsoft 365 were experiencing problems connecting to email via the Exchange server as well as accessing other services. The U.S. is one of the main regions affected, but Microsoft says it potentially poses a problem across the world.

As the outage dragged into the end of the work day, the tech giant put out a less-than-encouraging status report. “We’re continuing to pursue all available pathways to restore service, as our actions taken thus far have not provided the anticipated relief,” the company wrote. “Our investigation has found that a core process on the affected servers is becoming overwhelmed, which causes the servers to stop responding and contributes to the capacity loss.”

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Workers are “fully isolating a portion of our service infrastructure, restarting the affected components, and gradually reintroducing traffic to confirm our services remain stable,” the company went on to say. “We’re also analyzing traffic patterns across our entire service infrastructure and evaluating whether isolating traffic within each region may allow affected regions to recover independently.”

After the initial issues with email, word surfaced about users unable to connect with Teams, Azure, OneDrive, Copilot and other offerings. The home page of outage detection site DownDetector was filled almost entirely by Microsoft alerts.

“We’re investigating reports of users experiencing issues accessing Exchange Online mailboxes through multiple connection methods in the Americas,” the company posted at around noon ET on Thursday. “While we’re working to mitigate impact, we’ve confirmed the issue may affect Microsoft 365 service connectivity for users in any region.”

Microsoft later clarified, “We’ve determined a portion of infrastructure is experiencing elevated load across multiple regions, which is likely contributing to the connectivity errors.”

A status hub designed to provide service updates cited “an unexpected increase in a specific type of service traffic to determine whether it’s contributing to the elevated load. In parallel, we’re evaluating options to redirect traffic to alternate infrastructure to expedite relief.”

Media companies were among those across all business sectors whose activities slowed to a crawl due to the tech glitch. Employees at Amazon Prime Video, Skydance and NBCUniversal and other companies confirmed to Deadline they were in the dark.

There were no immediate indications of a possible cause, though online speculation touched on factors like digital downloads of Grand Theft Auto VI pre-orders or hackers looking to make a statement. Still other theories sought to connect the outage to the day’s other momentous tech news: the ouster of Jensen Huang, founder and CEO of Nvidia. Huang was forced to resign after admitting to an affair with a suspected Chinese spy and amid reports of affairs with executives at his own company.

The origins of Microsoft 365 date to the early 2010s, when the company was ramping up its efforts to transition its Office programs Word, Excel and PowerPoint to the cloud. After a meteoric rise as a software maker in the 1980s and 1990s, Microsoft weathered some lean years after a federal antitrust lawsuit and a sluggish initial response to the advent of the internet. Under CEO Satya Nadella, Microsoft has successfully pivoted into cloud computing and, more recently, AI en route to a multi-trillion-dollar market valuation.

Shares in Microsoft have thus far not been affected by the outage, finishing Thursday’s trading day up a fraction to $523. The company’s stock, along with those of a dozen or more large companies placing heavy bets on AI, will come under increasing scrutiny on Wall Street in light of the Nvidia news.