Slack has been down before.
In late May the company reported that some users had problems with the website. They were unable to edit or send messages, view threads, access channels, and create group DMs.
Slack had discovered at the time that an update to its website code caused a “significant impact” in their databases. This was the cause of the issue.
The company said at the time that “once we reversed the changes and our databases had been in a better state, this issue was resolved” for the affected users.
Most users took an hour or so to fix the issue.
According to Slack server logs, however, many users were still having issues sending messages up to 9 hours after the initial incident.