[BUG] Chrome extension not connecting to native messaging host (macOS 26.2)

[uitholland]

Preflight Checklist

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

What's Wrong?

Chrome extension (v1.0.40) never connects to the native messaging host. All calls to
mcp__claude-in-chrome__ tools return "Browser extension is not connected".

Running the native host manually shows MCP clients (Claude Code) connecting and
forwarding tool requests, but no browser client ever connects. The extension appears
installed and enabled, but doesn't establish the native messaging connection.

Environment: macOS 26.2, Claude Code 2.1.19, Chrome extension 1.0.40

What Should Happen?
The Chrome extension should connect to the native messaging host and respond to tool
requests (tabs_context_mcp, navigate, etc.)

Error Messages/Logs
Native host output shows:
[Claude Chrome Native Host] Initializing...
[Claude Chrome Native Host] Socket server listening for connections
[Claude Chrome Native Host] MCP client 1 connected. Total clients: 1
[Claude Chrome Native Host] Forwarding tool request from MCP client 1: execute_tool
{"type":"tool_request","method":"execute_tool","params":{"tool":"tabs_context_mcp","args
":{"createIfEmpty":true}}}
[Claude Chrome Native Host] MCP client 1 disconnected. Remaining clients: 0

Note: Only MCP clients connect. Browser client never appears.

Tool always returns: "Browser extension is not connected"

What Should Happen?

The Chrome extension should connect to the native messaging host and respond to tool
requests (tabs_context_mcp, navigate, etc.)

Error Messages/Logs

Native host output shows:
  [Claude Chrome Native Host] Initializing...
  [Claude Chrome Native Host] Socket server listening for connections
  [Claude Chrome Native Host] MCP client 1 connected. Total clients: 1
  [Claude Chrome Native Host] Forwarding tool request from MCP client 1: execute_tool
  {"type":"tool_request","method":"execute_tool","params":{"tool":"tabs_context_mcp","args
  ":{"createIfEmpty":true}}}
  [Claude Chrome Native Host] MCP client 1 disconnected. Remaining clients: 0

  Note: Only MCP clients connect. Browser client never appears.

  Tool always returns: "Browser extension is not connected"

Steps to Reproduce

1. Install Chrome extension from https://claude.com/chrome (v1.0.40)
2. Start Claude Code with: claude --chrome
3. Call tabs_context_mcp or run /chrome
4. Result: "Browser extension is not connected"

Troubleshooting attempted (all failed):

• Restarted Chrome multiple times
• Restarted Mac completely
• Reinstalled Chrome extension
• Toggled extension off/on
• Closed all Claude tab groups
• Disabled all other Chrome extensions
• Deleted and recreated native messaging config
• Started fresh Claude Code session with --chrome flag

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

No response

Claude Code Version

2.1.19

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

No response

[github-actions]

Found 3 possible duplicate issues:

1. Claude in Chrome browser extension not connecting to Claude Code CLI #20298
2. [BUG] Chrome MCP shows "connected" but tool calls fail with "not currently connected" #20557
3. Chrome extension not working after latest cursor update #20543

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

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