Changes / Anthropic / Degraded functionality for Claude Cowork on Windows
Anthropic: Major incident: Degraded functionality for Claude Cowork on Windows
Summary
Claude Cowork on Windows could not run local commands after a September 8 Windows update blocked workspace access to the computer’s drive; chat and file reading/editing still worked for most users. Anthropic rated the incident major, from 2026-09-10 15:54 UTC to 2026-09-14 19:14 UTC (4 days 3 h). Microsoft’s September 14 Windows update fixed it.
Machine-written from the diff below (Sol; type: incident degradation). Check the diff before relying on it.
What changed
Before: not present
After: Degraded functionality for Claude Cowork on Windows
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After: major
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After: resolved
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After: 2026-09-10 15:54 UTC
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After: 2026-09-14 19:14 UTC
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After: Claude Cowork
Before: not present
After: 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.
Before: not present
After: 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
First version of this incident archived by Rewindex. View the live incident.
History of this incident
| When (UTC) | Change | Kind |
|---|---|---|
| Major incident: Degraded functionality for Claude Cowork on Windows (this change) Claude Cowork on Windows could not run local commands after a September 8 Windows update blocked workspace access to the computer’s drive; chat and file reading/editing still worked for most users. Anthropic rated the incident major, from 2026-09-10 15:54 UTC to 2026-09-14 19:14 UTC (4 days 3 h). Microsoft’s September 14 Windows update fixed it. | Major incident |
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