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Claude Code Issues / #76374

[Cowork] mcp__workspace__bash sandbox VM fails to start — persistent multi-session outage

Open 💬 0 comments Opened Jul 10, 2026 by n3o255

Preflight Checklist

  • [x] I have searched existing issues and this hasn't been reported yet
  • [x] This is a single bug report (please file separate reports for different bugs)
  • [x] I am using the latest version of Claude Code

What's Wrong?

The isolated Linux VM (mcp__workspace__bash) used by Claude Cowork fails to start across ALL Cowork sessions — both existing and newly created ones. This has been ongoing for 10+ hours (since July 9, 2026).

Error messages observed (alternating):

  • "Workspace unavailable. The isolated Linux environment failed to start (VM connection timeout after 60 seconds)."
  • "Workspace still starting. The isolated Linux environment is booting in the background (usually 10–30 seconds). Try again shortly."

The VM never comes up. File tools (Read/Write/Edit) and Desktop Commander MCP work normally — only mcp__workspace__bash is affected.

Note: This is a Cowork-specific issue (not Claude Code CLI), filed here as it appears to share infrastructure.

What Should Happen?

The mcp__workspace__bash sandbox VM should start within 10–30 seconds and be accessible for running bash commands in the isolated Linux environment, as it normally does.

Error Messages/Logs

Workspace unavailable. The isolated Linux environment failed to start (VM connection timeout after 60 seconds). You can still use file tools directly.

-- alternates with --

Workspace still starting. The isolated Linux environment is booting in the background (usually 10–30 seconds). Try again shortly.

Steps to Reproduce

  1. Open any Claude Cowork session (new or existing)
  2. Run any mcp__workspace__bash command, e.g.: echo "test"
  3. Observe: VM times out after 60s with "failed to start" error
  4. Retry multiple times — error persists indefinitely
  5. Open a brand new Cowork session — same error occurs immediately
  6. Issue has persisted across 10+ hours and multiple independent sessions

Confirmed NOT affected: Read/Write/Edit file tools, Desktop Commander MCP, local Kali WSL2

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

N/A — Claude Cowork desktop app (not Claude Code CLI)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

  • Platform: Windows 11 ARM64, Claude Cowork desktop app
  • Account: neodragon255@gmail.com
  • Issue started: July 9, 2026 — ongoing as of July 10, 2026 (10+ hours)
  • Affected: ALL Cowork sessions (existing and newly created)
  • NOT affected: Read/Write/Edit file tools, Desktop Commander MCP, local Kali WSL2
  • Anthropic support email ticket already open (Fin AI Agent replied, confirmed no active incident listed on status.anthropic.com, but issue persists)
  • Model in use: claude-sonnet-4-6

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