On January 20, 2020 from 12:21 a.m. - 5:30 p.m. PST and January 21, 2020 from 9:30 a.m. - 9:40 a.m. PST, some customers experienced intermittent issues with sending messages in Slack. In particular, customers may have seen a "Slack couldn't send this message" error. These errors were a result of lag during one of our routine database changes, which caused significant delays when transferring the message data. Once we alleviated the delays, messages were delivered successfully once again.
For those affected, thank you for bearing with us. We're taking steps to ensure this doesn't occur again.
12:21 PM PST