Office messaging app Slack is down on the first Monday of 2021 as people return to their virtual work stations after New Year's eve.

The company said customers might have trouble loading channels or connecting to Slack and its team is investigating the cause.

Customers may be experiencing issues connecting and using Slack at this time. Our team is currently investigating and we’re sorry for any troubles this may be causing. Please see https://t.co/hlhV4Z15g6 for updates.

— Slack (@SlackHQ) January 4, 2021

“We will follow up with more information as soon as we have it. We apologize for any disruption caused.”

Many users reported issues with the app, including connection problem to servers and failing to send messages.