Wednesday September 12 - Saturday August 24, 2019


Connectivity issues affecting some users

Technical summary:
On September 12th from 9:59pm to 10:18pm Pacific Time, a few hundred people were not able to do connect to Slack.

A network event between servers in Slack’s central data centers caused normal login attempts to fail in such a way that people’s Slack clients retried aggressively. These retries were rate-limited by Slack’s servers in order to protect themselves. As soon as the network event was resolved by our data center provider, and as soon as rate limits allowed, people were once again able to connect to Slack.

The all clear was called at 11:05pm Pacific Time, after prolonged observation of network conditions.

4:18 PM PST

Everyone should be able to connect to Slack again. If you have any further trouble, please reach out at We really appreciate your patience as we worked through this.

10:18 PM PST

We're still digging in to this, but things are beginning to look up. Thank you for bearing with us.

10:14 PM PST

Some users may have trouble connecting to Slack. We're investigating and we're very sorry for the disruption to your day.

9:59 PM PST

Services affected