Is Claude Cowork down? › Outage history › Sep 10, 2026

Claude Cowork partial outage on Sep 10, 2026: what happened

On Sep 10, 2026, the Claude status page reported "Degraded functionality for Claude Cowork on Windows". About 4 days 3 hours: from Sep 10, 2026, 15:54 UTC to Sep 14, 2026, 19:14 UTC, by the official start and resolution times.

Claude Cowork right now

At our last refresh (Oct 22, 2026, 12:35 UTC) Claude Cowork was up: Operational.

Is Claude Cowork down right now? →
Started
Sep 10, 2026, 15:54 UTC
Resolved
Sep 14, 2026, 19:14 UTC
Duration
4 days 3 hours
Official impact
Major
Affected
Claude Cowork
Source
Degraded functionality for Claude Cowork on Windows on the Claude status page

The Claude status page rated the impact "Major": a partial outage. Some parts or some users were affected; it was not a complete outage.

What caused the Claude Cowork partial outage?

"A Windows update released September 8 has left Claude Cowork on Windows unable to run local commands, because its workspace can no longer reach your computer's drive."

From the Claude status page, Sep 10, 2026, 15:54 UTC.

When was it fixed?

The Claude status page marked it resolved at Sep 14, 2026, 19:14 UTC, 4 days 3 hours after it started. Its resolution note: "This issue has been resolved. Microsoft has released a September 14 Windows update that fixes it: https://support.microsoft.com/en-us/servicing/os/windows-11/2026/09/kb5129195-windows-11-24h2-25h2-security-update"

Timeline of official updates

Every update the Claude status page posted, oldest first. Times are UTC.

  1. Sep 10, 2026, 15:54 UTC identified

    A Windows update released September 8 has left Claude Cowork on Windows unable to run local commands, because its workspace can no longer reach your computer's drive. For most users, chat and file reading and editing still work. There's no in-app workaround yet, and restarting or reinstalling won't help. Microsoft has developed a fix and is working to release it. We'll post an update when we have more to share.

  2. Sep 14, 2026, 19:14 UTC resolved

    This issue has been resolved. Microsoft has released a September 14 Windows update that fixes it: https://support.microsoft.com/en-us/servicing/os/windows-11/2026/09/kb5129195-windows-11-24h2-25h2-security-update

The same incident was listed for Claude, which share Claude Cowork's status page.

Claude Cowork partial outage questions

What caused the Claude Cowork partial outage on Sep 10, 2026?

The Claude status page said (update at Sep 10, 2026, 15:54 UTC): "A Windows update released September 8 has left Claude Cowork on Windows unable to run local commands, because its workspace can no longer reach your computer's drive."

When was the Claude Cowork partial outage on Sep 10, 2026 fixed?

The Claude status page marked it resolved at Sep 14, 2026, 19:14 UTC, 4 days 3 hours after it started. Its resolution note: "This issue has been resolved. Microsoft has released a September 14 Windows update that fixes it: https://support.microsoft.com/en-us/servicing/os/windows-11/2026/09/kb5129195-windows-11-24h2-25h2-security-update"

How long did the Claude Cowork partial outage last?

About 4 days 3 hours: from Sep 10, 2026, 15:54 UTC to Sep 14, 2026, 19:14 UTC, by the official start and resolution times.

Was Claude Cowork completely down?

No. The Claude status page rated the impact "Major": a partial outage. Some parts or some users were affected; it was not a complete outage. The affected parts listed were: Claude Cowork.

Which parts of Claude Cowork were affected?

The Claude status page listed: Claude Cowork.

Other recent Claude Cowork incidents

Full Claude Cowork outage history and biggest outages → · Recent outages across all services →

Quotes are the Claude status page's own words, from the official incident. Is It Up or Down is independent and not affiliated with Claude Cowork. Times are UTC.