This Dec. 2, 2020, file photo shows the Slack app icon being displayed on a computer screen in Tokyo. Slack suffered a global outage Monday, Jan. 4, 2021, during the first day back to work for most people after the New Year's holiday. Users reported service was down in the U.S., Asia, Latin America Europe, and India. (AP Photo/Kiichiro Sato, File)

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 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.

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.