Slack, the messaging service used by millions of people for work and school, suffered a global outage on Monday, the first day back for most people returning from the New Year's holiday.

It's the latest tech glitch to show how disruptive technical difficulties can be when millions of people are depending on just a few services to work and go to school from home during the pandemic.

The company stopped releasing its daily user count after topping 12 million last year.

"Our team is currently investigating and we're sorry for any troubles this may be causing," Slack said in a prepared statement.

The outage began around 10 a.m. Eastern time and disrupted service in the U.S., Germany, India, the U.K., Japan and elsewhere. At 12:30 p.m., service was still sporadic and Slack said the outage was ongoing, but that some users may begin to see improvement. Slack said that people should check https://status.slack.com for updates. Most issues were resolved by 3 p.m. on Monday afternoon.

Internet service outages are not uncommon, are usually resolved relatively swiftly and are only rarely the result of hacking or other intentional mischief. Google went down briefly in December, with people in several countries briefly unable to access their Gmail accounts, watch YouTube videos or get to their online documents during an outage Monday. In August, Zoom went down briefly just as many students were beginning the school year at home. And in September, Microsoft services had an outage that lasted for five hours.

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More complaints rolled in as the sun hit the West coast and there were still outages four hours after it began in New York City.

The outage comes about a month after Salesforce.com said it would acquire Slack for $27.7 billion. The companies hope to be better able to compete against Microsoft, which is a threat to both of them.

Slack is being acquired by Salesforce.com for $27.7 billion. The deal is aimed at giving the two companies a better shot at competing against longtime industry powerhouse Microsoft.

Microsoft Teams is a direct competitor to Slack and it is a software giant that competes with Salesforce.