Sunday June 1, 2025

On June 1, 2025, beginning around 5:00 PM PDT until 6:29 PM PDT, some users experienced issues with connecting to or logging into Slack, sending or receiving messages including those that were scheduled, and trouble loading items such as 'Activity' view.

We traced the issue to a backend caching system that began improperly serving traffic in one of our database regions. As a result, an increase in error rates occurred for many Slack features. An automated recovery system began shifting failed requests to healthy databases, allowing success for some users.

To fully mitigate the impact, we temporarily rerouted traffic away from the affected backend service, allowing it to recover. After addressing the issue with the caching system, we directed traffic back to the service once it was functioning properly, resolving the issue for all affected users.

3:15 PM PST

Customers should no longer be experiencing any trouble connecting to Slack or sending messages. Apologies for the trouble today and thank you for your patience. 

7:31 PM PST

We've deployed a fix and we're seeing improvements. We are monitoring the situation closely, and we'll be back once we can confirm that everything is running normally again. 

If you're still experiencing issues, please try refreshing Slack with Cmd/Ctrl + Shift + R. 

6:56 PM PST

We are still working to investigate this issue, and we'll be back with another update in 30 minutes. Thank you for bearing with us.

6:28 PM PST

A small number of users may be unable to connect to Slack or send messages at the moment. We apologize for the disruption. We are working to resolve this as our highest priority, and we'll provide another update in 30 minutes.

5:57 PM PST