---
id: "INC-anthropic-r1pqn1kb4hvk"
kind: "incident"
aliases: []
title: "Anthropic: Degraded functionality for Claude Cowork on Windows"
severity: "high"
cvss: null
epss: null
exploited: false
status: "resolved"
category: "vendor"
products: [{"name": "Anthropic", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["ai", "anthropic", "claude-cowork", "incident", "llm", "security", "vendor", "windows"]
not_affected_if: ["non-windows-platforms"]
published_at: "2026-09-10T15:54:10+00:00"
first_seen_at: "2026-10-23T19:12:22+00:00"
updated_at: "2026-10-23T21:50:52+00:00"
sources: [{"source": "statuspage", "url": "https://stspg.io/5yp3rhhztm30", "first_seen_at": "2026-10-23T19:12:22+00:00"}]
---

# Anthropic: Degraded functionality for Claude Cowork on Windows

Anthropic's status page reported degraded functionality for Claude Cowork on Windows, and the incident is marked resolved. The sources do not describe an attacker-usable flaw; the cause was a Windows-side issue fixed by Microsoft's September 14 update.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Anthropic affected ? fixed ?

## Fix

Install the Microsoft Windows 11 September 14 security update (KB5129195 for 24H2/25H2) as linked in the incident; the incident itself is resolved.

## Timeline

- 2026-10-23T19:12:22+00:00 statuspage https://stspg.io/5yp3rhhztm30

## From the sources

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

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_