Slack Outage History

Slack experienced intermittent SSO login failures that prevented some users from accessing their workspaces for 2.4 hours. The issue specifically affected the Login/SSO components, causing authentication problems for users attempting to sign in. The incident was classified as minor and the team worked to investigate and resolve the login failures.

Slack experienced a 25.8-hour incident that began with delayed enterprise grid migrations and expanded to affect app mentions, mobile push notifications, and workspace administration. Users were unable to receive responses when @mentioning apps in channels, org admins experienced migration delays, and mobile push notifications failed to deliver. Slack resolved the issue by increasing processing capacity, deploying code changes to fix delayed job processing, and clearing the message backlog to restore normal platform functionality.

Slack's search functionality was severely degraded for International Data Residency (IDR) users in the Middle East (Dubai) region due to significant physical infrastructure damage at regional AWS data centers, including loss of power and cooling. The incident affected search performance and caused search failures, while other Slack services in the region continued operating normally. The issue was resolved after 57.9 hours through collaboration with AWS to restore data access and recover missing data shards and database records.

Slack's Search feature experienced issues causing users to encounter errors or delays when attempting to search. The incident affected the Search component and lasted 6.5 hours. The service team actively investigated the problem during this period.

Slack experienced a 4.5-hour email delivery issue where some users couldn't receive confirmation codes and invitations, preventing them from completing login processes or accepting invitations. The problem was caused by a missing data field in Slack's email validation system that incorrectly blocked messages through suppression list checks. Slack deployed a fix across their infrastructure to restore email delivery functionality for all affected users.

Slack experienced a 4.8-hour outage affecting direct messaging functionality, where users could not add people to multi-person direct messages and some encountered errors when sending messages. The issue was caused by increased load on a messaging-related service. Slack resolved the problem by reducing the load and adding additional capacity, restoring full messaging functionality.