Wednesday May 20, 2020

Issue Summary:
On May 20, 2020 from 8:36 a.m. PDT until 8:52 a.m. PDT, some customers were unable to connect to Slack.

We determined that a code change designed to prevent out-of-memory errors was unintentionally reading from an outdated cache under certain conditions, resulting in our databases becoming temporarily overloaded.

We reverted the code change as soon as we identified this problem. This restored full functionality for all impacted customers.

11:22 AM PST

From 8:36 a.m. PDT to 8:52 a.m. PDT, some customers were not able to connect to Slack. Our engineers worked quickly to identify the issue and service was fully restored.

We are conducting our standard postmortem process and will provide a full technical summary shortly.

We're very sorry for the disruption.

8:52 AM PST