Slack outage on Sep 12, 2026

What happened

Slack reported a partial outage starting Sep 12, 2026, 11:04 UTC. It was marked resolved at Sep 12, 2026, 20:00 UTC.

• The incident lasted 8h 56m from first report to resolution.
• Slack had reported 6 other partial or major outages in the 90 days before it.
• 2 other vendors we track reported a significant incident within 12 hours of it.

Latest update from Slack

4:04am PDT We're aware there's an issue where a subset of customers are experiencing blurry images which can't be downloaded, this is happening across all clients. We're actively working to understand the cause, scope, fix, or other details.  4:29am PDT We've identified a likely technical trigger connected to a recent image-rendering service change.Current status and actions being taken: We have identified a likely technical trigger — a recent thumbnail-sharpening change to the image-rendering service. We're working to validate this, and are evaluating the rollback of the change as a possible fix.Estimated time to resolution: We are still confirming the technical trigger before a fix can be scoped.Scope: Affects a subset of customers across desktop, web, and mobile clientsCurrent impact to end users: Images uploaded before roughly 9:30 PM GMT on Sep 11 appear blurry in previews and fail to download. Newly uploaded images are unaffected.Known workarounds: None identified yet.We app

Read Slack's official incident report ↗

What our independent monitoring saw

Our independent monitoring of Slack started after this incident, so this report is based on Slack's status page.

Other outages around the same time

Significant incidents other vendors reported within 12 hours of this one.

• Partial outageMetronomeSep 11, 2026, 23:22 UTC

  Elevated API Error Rate

• Partial outageShippoSep 12, 2026, 21:47 UTC

  Elevated error rate on Royal Mail_SF Tracking

Slack's overall reliability

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