Claude in Chrome: Native messaging host never called - browser automation tools fail to connect

Resolved 💬 3 comments Opened Jan 28, 2026 by elad-refoua Closed Feb 1, 2026

Environment

| Property | Value |
|----------|-------|
| Claude Code Version | 2.1.22 |
| Windows Version | 10.0.26100.7623 |
| Chrome Version | (not specified in debug log) |
| Extension ID | fcoeoabgfenejglbffodgkkbkcdhcgfn |
| Extension Version | 1.0.40 |
| Platform | Windows 10 |

---

Problem Description

Browser automation tools in Claude in Chrome fail to connect with the following error:

"Browser extension is not connected. Please ensure the Claude browser extension is installed and running"

All MCP Claude-in-Chrome tools are unavailable:

mcp__claude-in-chrome__computer
mcp__claude-in-chrome__read_page
mcp__claude-in-chrome__navigate
All other browser automation tools

The extension appears functional and is installed, but no connection is established.

---

Steps to Reproduce

Install Claude Code CLI version 2.1.22 on Windows 10
Install Claude in Chrome browser extension (v1.0.40)
Configure native messaging host with correct registry entry and manifest file
Start Claude Code with --chrome flag
Attempt to use any mcp__claude-in-chrome__* tool
Observe: Connection error is displayed

---

Expected vs Actual Behavior

Expected

Extension initiates native messaging connection to the host
Browser automation tools execute successfully
mcp__claude-in-chrome__* tools are available in the tool list

Actual

Extension does not initiate native messaging connection
Native host is never called (verified through debug logging)
All browser automation tools fail with "not connected" error
Extension appears installed and enabled but is non-functional

---

Debugging Performed

Configuration Verification - All Components ✓ Correct

1. Registry Entry

Path: HKCU\SOFTWARE\Google\Chrome\NativeMessagingHosts\com.anthropic.claude_code_browser_extension
Value points to correct manifest file location: ✓

2. Native Messaging Manifest File

Location: C:\Users\user\AppData\Roaming\Claude Code\ChromeNativeHost\com.anthropic.claude_code_browser_extension.json
JSON structure correct with all required fields: ✓
allowed_origins contains correct extension ID: chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/ ✓

3. Native Host Script

Location: C:\Users\user\.claude\chrome\chrome-native-host.bat
Script structure correct: ✓
Points to correct Claude executable: C:\Users\user\.local\bin\claude.exe ✓

4. Claude Executable

Location: C:\Users\user\.local\bin\claude.exe
Version: 2.1.22 (meets minimum requirement 2.0.73+): ✓
File exists and is executable: ✓

5. Chrome Extension

Installation status: ✓ Installed
ID: fcoeoabgfenejglbffodgkkbkcdhcgfn ✓
Version: 1.0.40 (meets minimum requirement 1.0.36+): ✓
No errors in chrome://extensions: ✓

6. Claude Code Settings

/chrome command shows status: Enabled ✓
Extension integration: Approved/Enabled ✓

Troubleshooting Attempted

| # | Action | Result |
|---|--------|--------|
| 1 | Verify registry entry | Present and correct ✓ |
| 2 | Verify manifest file | Present and correct ✓ |
| 3 | Verify native host script | Present and correct ✓ |
| 4 | Verify claude.exe exists | Present ✓ |
| 5 | Start with --chrome flag | Applied, no change |
| 6 | Restart Chrome | No effect |
| 7 | Restart Claude Code | No effect |
| 8 | Full restart sequence | Chrome → Extension → Claude Code, no effect |
| 9 | Check MCP servers list | Chrome not listed (only brave-search, tavily available) |
| 10 | Use "Reconnect extension" option | No effect |
| 11 | Open extension side panel | Panel opens but still no connection |
| 12 | Reinstall extension | Performed twice, no change |
| 13 | Check chrome://extensions | No errors reported |
| 14 | Developer mode inspection | Service worker inspect option unavailable |

---

Key Finding

The native host batch file is NEVER called by the extension.

Debug logging was added to the native host batch script:

@echo off
echo [%date% %time%] Native host called >> "C:\Users\user\.claude\chrome\native-host.log"
"C:\Users\user\.local\bin\claude.exe" --chrome-native-host >> "C:\Users\user\.claude\chrome\native-host.log" 2>&1

Result: No log file was ever created. This definitively proves:

The Chrome extension is NOT initiating the native messaging connection
The issue is 100% on the extension side, not the native host configuration
All native host configuration is correct and ready to receive a connection

---

Technical Details

Native Messaging Manifest

{
  "name": "com.anthropic.claude_code_browser_extension",
  "description": "Claude Code Browser Extension Native Host",
  "path": "C:\\Users\\user\\.claude\\chrome\\chrome-native-host.bat",
  "type": "stdio",
  "allowed_origins": [
    "chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/"
  ]
}

Native Host Batch File

@echo off
REM Chrome native host wrapper script
REM Generated by Claude Code - do not edit manually
"C:\Users\user\.local\bin\claude.exe" --chrome-native-host

MCP Availability

Available servers: brave-search, tavily
Missing server: chrome (should appear as mcp__claude-in-chrome__* when connected)

---

Possible Root Causes

Extension not initiating native messaging connection - The extension may have a bug preventing it from calling the native messaging API
Silent failure in extension - Native messaging connection attempt may be failing silently with no error reporting
Version incompatibility - Potential incompatibility between extension v1.0.40 and Claude Code v2.1.22
Windows-specific issue - Native messaging may have Windows-specific requirements not being met by the extension
Chrome permissions issue - Chrome may need specific permissions to allow this extension to use native messaging

---

Affected Components

Claude in Chrome browser automation tools (all tools using mcp__claude-in-chrome__ prefix)
Browser tab management
Page reading and inspection
Element interaction (click, scroll, type, etc.)
Screenshot and recording capabilities
Network and console monitoring

---

Workaround

Currently none available. All browser automation tools are blocked by this connection failure.

---

Additional Notes

Extension reinstalled twice with no improvement
All verification steps confirm configuration is 100% correct
Issue is reproducible and consistent
No intermittent connectivity - connection never established at all

---

Related Files

Extension log location: C:\Users\user\AppData\Roaming\Claude Code\ChromeNativeHost\
Extension ID: fcoeoabgfenejglbffodgkkbkcdhcgfn
Debug log path: C:\Users\user\.claude\chrome\native-host.log (not created due to extension bug)

---

Suggested Resolution Path

Verify that Claude in Chrome extension is initiating the native messaging connection in its service worker
Check for silent failures or exceptions in native messaging initialization
Verify that the extension calls chrome.runtime.connectNative() with the correct host name: com.anthropic.claude_code_browser_extension
Test native messaging functionality in a clean Chrome profile
Check for Windows API compatibility issues with the native messaging IPC mechanism

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