Chrome extension not connecting to Claude Code via native messaging on Windows 11

[sinxsarah]

Bug Report:

Environment

• OS: Windows 11 Version 25H2 (Build 26200.7623)
• Claude Code version: 2.1.20 (also tested with native installer)
• Chrome version: 144.0.7559.97
• Chrome extension version: 1.0.40
• Extension ID: fcoeoabgfenejglbffodgkkbkcdhcgfn

Issue

All mcp__claude-in-chrome__* tools return "Browser extension is not connected" despite correct configuration.

The same extension works for Claude.ai MCP connections but will not initiate native messaging for Claude Code.

What we've verified

• Registry entry exists:
  HKCU\Software\Google\Chrome\NativeMessagingHosts\com.anthropic.claude_code_browser_extension
• Native host JSON has correct extension ID in allowed_origins
• Native host batch file exists and points to valid Claude Code executable
• Extension has "Communicate with cooperating native applications" permission
• No conflicting Claude Desktop registry entries

Troubleshooting attempted

• Killed all node/chrome processes and restarted in various orders
• Uninstalled and reinstalled Chrome extension
• Removed and recreated native host config files
• Installed Claude Code native version via claude install
• Removed conflicting Claude Desktop native host registry entry

Key finding

When manually running the native host batch file, it attempts to CREATE a named pipe
(\\.\pipe\claude-mcp-browser-bridge-[username]) rather than connect to an existing one, causing EADDRINUSE errors
when the MCP bridge is already running.

The extension service worker shows NO activity when Claude Code attempts to use Chrome tools - it's not even
attempting to initiate native messaging.

Expected behavior

Extension should connect to Claude Code's MCP bridge via native messaging.

Actual behavior

Extension ignores native messaging entirely. Works for Claude.ai web MCP but not Claude Code.

[github-actions]

Found 3 possible duplicate issues:

1. [Bug] Claude in Chrome MCP bridge fails on Windows - socket discovery doesn't find named pipes #21337
2. Chrome extension not connecting on Windows 11 (Build 26200) #21330
3. [BUG] Chrome extension v1.0.40 does not connect to Claude Code CLI --chrome on Windows #21240

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
• To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

[bardal]

Same here. Have uninstalled/reinstalled everything and no change

MCP server shows "Successfully connected" in debug logs, but tabs_context_mcp returns
"Browser extension is not connected"
Extension side is silent: Service worker DevTools console shows no activity when Claude Code calls Chrome tools -
extension never attempts native messaging
Side panel works: Extension UI functions normally, but no connection to Claude Code CLI

[bardal]

Workaround downgrade to 2.1.19
& ([scriptblock]::Create((irm https://claude.ai/install.ps1))) 2.1.19