Claude Code Desktop: New sessions fail with "Setup script failed with exit code 1" — existing sessions unaffected

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?

Environment:

• Claude Desktop App: 1.1.9493
• Claude Code CLI: 2.1.87
• macOS: 26.3.1 (Tahoe)
• Chip: Apple M4
• Node: v25.8.1

Description:

New Claude Code sessions in the desktop app consistently fail with "Setup script failed with exit code 1."
Existing/older sessions continue to work normally. The issue has persisted since March 23, 2026 — nearly a week now.

Steps to reproduce:

1. Open Claude desktop app
2. Start a new Claude Code session (any project directory)
3. Session fails immediately with "Setup script failed with exit code 1"

What I've tried (none of these fixed it):

• Reinstalled Claude Code CLI (npm install -g @anthropic-ai/claude-code)
• Cleared all Claude Code caches (~/Library/Application Support/Claude/claude-code, claude-code-vm, vm_bundles, Cache,

GPUCache)

• Completely uninstalled and reinstalled Claude desktop app via Homebrew
• Logged out and logged back in
• Killed and relaunched the app multiple times

Log analysis:

The VM boots and connects successfully — all backend logs (cowork_vm_node.log, coworkd.log, main.log) show clean
startup with no errors. The SDK installs correctly. The problem is in the web frontend.

claude.ai-web.log shows a recurring pattern on every new session attempt:

[REACT_QUERY_CLIENT] QueryClient error: Error: Not found
Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'includes')

The QueryClient fetch returns "Not found", and subsequent code calls .includes() on the undefined result, crashing the
session init.

Additionally, a Content Security Policy error appears:
Connecting to 'https://a-api.anthropic.com/v1/m' violates the following Content Security Policy directive:
"connect-src 'self' https://api.segment.io ..."

Timeline:

• First occurrence: 2026-03-23 14:20:55
• Latest occurrence: 2026-03-29 15:06:40
• Ongoing for ~6 days with no resolution

Key observation:

• Old/existing sessions work fine
• Only new session creation is broken
• Fresh app reinstall does not fix it, suggesting a server-side or account-level issue
• CLI (claude in terminal) works perfectly

What Should Happen?

When clicking "New Session" or starting a new Claude Code conversation in the desktop app, it should initialize successfully and present an interactive prompt ready for input.

Error Messages/Logs

From ~/Library/Logs/Claude/claude.ai-web.log (repeating since 2026-03-23):                                            
                                                                            
  [REACT_QUERY_CLIENT] QueryClient error: Error: Not found                                                              
  Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'includes')
                                                                                                                        
  Also present:                                                                                                         
  Connecting to 'https://a-api.anthropic.com/v1/m' violates the following Content Security Policy directive:
  "connect-src 'self' https://api.segment.io https://*.segment.io https://*.segment.com https://a-cdn.anthropic.com     
  https://*.google.com https://*.facebook.com https://*.facebook.net https://*.doubleclick.net". The action has been    
  blocked.                                                                                                          
  Fetch API cannot load https://a-api.anthropic.com/v1/m. Refused to connect because it violates the document's Content 
  Security Policy.                                                                                                     
  Error sending segment performance metrics TypeError: Failed to fetch
                                                                      
Note: All backend/VM logs are clean. VM boots, SDK installs, network connects, API is reachable. The failure is entirely in the web frontend layer.

Steps to Reproduce

1. Open Claude desktop app (v1.1.9493)
2. Click to start a new Claude Code session (any directory)
3. Session fails with "Setup script failed with exit code 1"
4. Existing/older sessions continue to work normally

Troubleshooting already attempted (none resolved it):

• Reinstalled Claude Code CLI via npm
• Cleared ~/Library/Application Support/Claude/claude-code, claude-code-vm, vm_bundles, Cache, GPUCache
• Completely uninstalled and reinstalled Claude desktop app (via brew install --cask claude)
• Logged out and back in
• Killed and relaunched app multiple times

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unsure of exact version. Issue first appeared on 2026-03-23. App was working before that date.

Claude Code Version

2.1.87 (Claude Code)

Platform

Other

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

• The bug has been active for 6 days (first error: 2026-03-23 14:20:55, latest: 2026-03-29 15:06:40)
• ONLY new sessions are affected — existing sessions work fine
• The CLI (running claude in terminal) works perfectly, confirming this is a desktop app frontend issue
• The VM backend is fully healthy: boots in ~13s, SDK installs, network connects, API reachable
• The root cause appears to be a React QueryClient fetch returning "Not found", after which code calls .includes() on

the undefined result

• A fresh app reinstall did not fix it, suggesting the issue is server-side or account-level rather than a local

corruption

• Node v25.8.1, npm via Homebrew on Apple Silicon