[BUG] Claude Desktop MCP shows "Browser extension is not connected" despite chrome-native-host process running and side panel working (macOS)

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 Claude in Chrome extension's MCP bridge to Claude Desktop stopped working mid-session. The chrome-native-host process is running and the extension's side panel works correctly, but all MCP tool calls from Claude Desktop return "Browser extension is not connected."

This was working earlier today with no configuration changes. The issue appeared suddenly and persists through full app restarts, extension reinstall, and process restarts.

Environment

• OS: macOS (corporate managed)
• Claude Desktop: Latest (chrome-native-host binary dated Feb 5, 2026)
• Chrome Extension: v1.0.45 (reinstalled fresh)
• Chrome: Latest
• Plan: Max
• Endpoint Security: CrowdStrike Falcon, VMware Carbon Black, Jamf

Steps to Reproduce

1. Have Claude Desktop open with Claude in Chrome connector enabled
2. Have Chrome open with Claude extension installed, authorized, and logged in (same account)
3. In Claude Desktop chat, trigger any Chrome MCP tool (e.g., tabs_context_mcp)
4. Receive "Browser extension is not connected" error

Diagnostics Performed

• ✅ Same account (robertcfoy@gmail.com) on both Desktop and Chrome extension
• ✅ Connector enabled in Desktop Settings → Connectors → Claude in Chrome
• ✅ Extension enabled with "On all sites" access
• ✅ Native messaging host file exists at ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json
• ✅ Config points to correct binary: /Applications/Claude.app/Contents/Helpers/chrome-native-host
• ✅ Binary exists with execute permissions (-rwxr-xr-x)
• ✅ Extension ID (fcoeoabgfenejglbffodgkkbkcdhcgfn) is in allowed_origins
• ✅ chrome-native-host process IS running: ps aux shows /Applications/Claude.app/Contents/Helpers/chrome-native-host chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/
• ✅ Extension side panel works independently (can see tabs, respond to queries)
• ❌ MCP tool calls consistently return "Browser extension is not connected"

Troubleshooting Attempted

• Full quit (Cmd+Q) and restart of both Chrome and Claude Desktop (multiple times)
• Toggled Claude in Chrome connector off/on in Desktop settings
• Completely removed and reinstalled Chrome extension
• Logged out and back into extension
• Killed chrome-native-host process and restarted Chrome
• Tried switch_browser MCP command
• Started new chat sessions in Claude Desktop

Key Observation

The chrome-native-host process spawns and runs, and the extension side panel works independently. The disconnect is specifically between the MCP layer in Claude Desktop and the extension's native messaging bridge — identical to issues #22500, #21796, and #20789.

Expected Behavior

MCP tool calls from Claude Desktop should connect to the Chrome extension and return tab/page information.

Actual Behavior

All MCP tool calls return "Browser extension is not connected" despite the native host process running and all configuration being correct. Was working earlier the same day with no changes.

What Should Happen?

MCP tool calls from Claude Desktop (e.g., tabs_context_mcp) should connect to the Chrome extension and return tab/page information, enabling browser automation from Desktop.

Error Messages/Logs

All MCP tool calls return:
"⚠️ Claude in Chrome Extension Disconnected - The connection to Claude in Chrome was lost."

Despite chrome-native-host process running:
$ ps aux | grep chrome-native-host
robertfoy  57099  0.0  0.0  410121888  3520  ??  S  6:49AM  0:00.01 /Applications/Claude.app/Contents/Helpers/chrome-native-host chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/

Native messaging host config:
$ cat ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json
{
  "name": "com.anthropic.claude_browser_extension",
  "description": "Claude Browser Extension Native Host",
  "path": "/Applications/Claude.app/Contents/Helpers/chrome-native-host",
  "type": "stdio",
  "allowed_origins": [
    "chrome-extension://dihbgbndebgnbjfmelmegjepbnkhlgni/",
    "chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/",
    "chrome-extension://dngcpimnedloihjnnfngkgjoidhnaolf/"
  ]
}

System log access blocked by corporate policy:
$ log show --predicate 'process == "chrome-native-host"' --last 5m
log: Could not open local log store: Operation not permitted

Steps to Reproduce

1. Open Claude Desktop (Max plan, macOS)
2. Open Chrome with Claude in Chrome extension v1.0.45 installed and authorized
3. Confirm same account on both, connector enabled in Desktop Settings → Connectors
4. Confirm chrome-native-host process is running: ps aux | grep chrome-native-host
5. In Claude Desktop chat, trigger any Chrome MCP tool (e.g., tabs_context_mcp)
6. Result: "Browser extension is not connected" despite native host process running
7. Extension side panel works independently during this time

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

this is claude desktop issue

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Additional Context

• This issue was working earlier the same day (Feb 6, 2026) with no configuration changes
• Corporate macOS with CrowdStrike Falcon, VMware Carbon Black, and Jamf endpoint security
• Extension side panel works independently (can see tabs, interact with pages)
• Only the MCP bridge from Claude Desktop → extension is broken
• Claude Desktop version: Latest as of Feb 6, 2026 (Max plan, Opus 4.6)
• Chrome extension version: 1.0.45
• Similar to #22500, #21796, #20789

Troubleshooting Attempted

• Full quit and restart of both Chrome and Claude Desktop (multiple times)
• Toggled connector off/on in Desktop settings
• Completely removed and reinstalled Chrome extension
• Logged out and back into extension
• Killed chrome-native-host process and restarted
• Tried switch_browser MCP command
• Started new chat sessions in Claude Desktop
• Full machine reboot