On the first day of the first workweek of 2021, Slack had a meltdown.

The popular workplace chat app confirmed Monday that customers were experiencing trouble connecting to or using the platform but did not share details about the scope or markets affected. But according to the website Downdetector, which displays outage reports in many metropolitan hubs, the disruption affected users throughout the United States, the United Kingdom, Brazil, France, Japan and beyond.

The service interruptions were first reported at 10:15 a.m. Eastern time. Slack started working again for some users around midday. By 2:30 p.m., the company confirmed that service had largely been restored save for a few hiccups.

The San Francisco-based company did not say what caused the outage but noted on its service page that it affected users’ ability to log in, message or share files.

In an emailed statement Monday morning, Slack said that it was looking into the problem: “We know how important it is for people to stay connected and we are working hard to get everyone running as normal.”

Slack has been transparent about its outages in the past. In May, the company published a detailed blog post about server scaling issues that contributed to a major service disruption. The outage, which was resolved the same day, was at least partly tied to the spike in usage the company has seen since the pandemic pushed large segments of the workforce to work remotely.

“We strive to keep Slack available and reliable, and in this case, we failed,” engineer Laura Nolan wrote in the May post, after a detailed technical explanation of the incident. “We know that Slack is a critical tool for our users, and that is why we aim to learn as much as we can from every incident, whether customer visible or not.”

The communications platform has thrived during the pandemic as offices have moved to virtual workplaces and leaned more heavily on productivity software to get work done without in-person meetings. Slack added 12,000 net paid customers, according to the company’s latest earnings report, up 140 percent from the same period last year. Revenue swelled by 39 percent to $234.5 million. In October, the messaging app listed more than 12 million daily users.

Enterprise software company Salesforce entered a deal to buy Slack for nearly $28 billion in December. The sale is expected to close this year.

Workers returning from holiday breaks took to Twitter to comment about the Monday outage.

“If Slack is down for 15 minutes the work day is canceled. I don’t make the rules,” one user wrote.

“Slack going down the first day back to work in 2021 is how we all feel about today,” another tweeted.