Cowork VM fails to start on Windows 11 — "Claude Code process exited with code 1" persists after clean reinstall

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?

Cowork fails to start any session on Windows 11. Every attempt returns the error "Claude Code process exited with code 1". The error persists after a complete clean reinstall.

Before the reinstall, the app showed the message: "Reinstalação necessária — O Cowork requer que o Claude Desktop seja instalado por meio de um instalador moderno" ("Reinstallation required — Cowork requires Claude Desktop to be installed via a modern installer"). I followed the instruction: uninstalled the existing Claude Desktop, downloaded the latest installer from https://claude.com/download, and installed the new version. After reinstall and fresh login, the Cowork VM still fails to start with the same exit code 1.

A separate error panel also appeared earlier during the same issue: "Não foi possível iniciar o espaço de trabalho do Claude — VM service not running. The service failed to start" ("Could not start Claude workspace — VM service not running. The service failed to start.")

Regular Claude.ai (browser) works normally with the same account. The issue is specific to the Cowork VM on the desktop app.

Troubleshooting already performed:

• Checked environment variables: no ANTHROPIC_API_KEY set (neither user nor system scope)
• Hardware virtualization is enabled in BIOS (confirmed via Task Manager → Performance → CPU → Virtualization: Enabled)
• Full uninstall of Claude Desktop, followed by clean install of the latest version from https://claude.com/download
• Fresh login with the same account used on Claude.ai (which works normally)
• No antivirus/firewall changes; no system configuration was modified by the user

The error persists after all the above.

What Should Happen?

Cowork should successfully initialize its VM and start a new session when the user opens the app, allowing normal use of workspace features (file access, code execution, conversation continuation). After a clean reinstall using the latest official installer, no "exit code 1" error should occur.

Error Messages/Logs

Primary error (shown in chat window on every attempt):
Claude Code process exited with code 1

Secondary error panel (shown when trying to resume an existing Cowork conversation):
Não foi possível iniciar o espaço de trabalho do Claude
VM service not running. The service failed to start.
Reiniciar o Claude ou seu computador às vezes resolve isso. Se persistir, você pode reinstalar o workspace.

Pre-reinstall message (which triggered the clean reinstall):
Reinstalação necessária
O Cowork requer que o Claude Desktop seja instalado por meio de um instalador moderno.

Steps to Reproduce

1. Open Claude Desktop on Windows 11
2. Attempt to start a new Cowork session OR resume an existing Cowork conversation
3. The error "Claude Code process exited with code 1" appears immediately
4. For existing conversations, an additional panel appears: "VM service not running. The service failed to start"

This happens on 100% of attempts, with no variation in steps required. The failure is immediate upon any Cowork session initialization attempt.

Reinstall procedure performed (and did NOT fix the issue):

1. Settings → Apps → Installed apps → Uninstall Claude Desktop
2. Downloaded the latest installer from https://claude.com/download
3. Installed the new version
4. Logged in with the same account used on Claude.ai (which works normally in the browser)
5. Attempted to use Cowork → error persists identically

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

I do not remember the exact version number, but Cowork was working normally on this same Windows 11 machine in previous weeks. The issue appeared suddenly, which is what prompted the "Reinstalação necessária" message from the app itself requesting installation via a modern installer.

Claude Code Version

N/A — Cowork on Claude Desktop (not Claude Code CLI). Using the latest version installed from https://claude.com/download on April 16, 2026.

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

IMPORTANT CLARIFICATION: This bug report is about Claude Cowork (the workspace/VM feature inside the Claude Desktop app), NOT the Claude Code CLI. The form title says "Claude Code" but this appears to be the same issue tracker for Cowork-related bugs.

Context:

• The issue is isolated to the Cowork VM subsystem on Windows 11
• Claude.ai in the browser works normally with the same account
• Hardware virtualization is confirmed enabled (Task Manager → Performance → CPU → Virtualization: Enabled)
• No ANTHROPIC_API_KEY environment variable is set (checked in both user and system scopes)
• Full clean reinstall from https://claude.com/download did NOT resolve the issue
• The app itself displayed the message "Reinstalação necessária — O Cowork requer que o Claude Desktop seja instalado por meio de um instalador moderno" before the reinstall, indicating a version/installer mismatch that the reinstall should have fixed — but did not

Impact: Unable to use Cowork at all. I rely on Cowork for professional work (legal and financial document analysis) and am currently blocked. Screenshots of the error panels are available upon request.