Chrome Mcp Troubleshooting

by trailofbits82fe82262526No license7.4K starsListed Oct 8, 2026Updated Oct 8, 2026Repository updated yesterday

Diagnose and fix Claude in Chrome MCP extension connectivity issues. Use when mcp__claude-in-chrome__* tools fail, return "Browser extension is not connected", or behave erratically.

Instructions onlySoftware Development
AI-generated overview

Diagnoses and fixes Claude in Chrome MCP extension connectivity failures on macOS, mainly native host conflicts.

What it does
Provides a macOS-focused troubleshooting guide for Claude in Chrome MCP browser tools that fail to connect or behave erratically. It explains the conflict between the Claude.app (Cowork) and Claude Code CLI native messaging hosts and their incompatible socket formats, then gives shell commands to disable one config, run a toggle function, inspect processes and sockets, and perform a full reset. It also covers other causes such as multiple Chrome profiles, multiple Claude Code sessions, a hardcoded version in the wrapper, and an unset TMPDIR.
When to use it
Use it when mcpclaude-in-chrome* tools report that the browser extension is not connected, time out, or work unreliably, especially after updating Claude Code or Claude.app or when switching between the CLI and the desktop app. It is not intended for Linux or Windows, general Chrome automation problems, desktop app issues, network problems, or extension installation.
Requirements
macOS with Chrome and the Claude extension, plus Claude Code CLI or Claude.app; shell access to run commands such as ps, lsof, pkill, mv, osascript and getconf. No scripts ship with the skill; commands are provided as instructions.

Claude in Chrome MCP Troubleshooting

Use this skill when Claude in Chrome MCP tools fail to connect or work unreliably.

When to Use

  • mcp__claude-in-chrome__* tools fail with "Browser extension is not connected"
  • Browser automation works erratically or times out
  • After updating Claude Code or Claude.app
  • When switching between Claude Code CLI and Claude.app (Cowork)
  • Native host process is running but MCP tools still fail

When NOT to Use

  • Linux or Windows users - This skill covers macOS-specific paths and tools (~/Library/Application Support/, osascript)
  • General Chrome automation issues unrelated to the Claude extension
  • Claude.app desktop issues (not browser-related)
  • Network connectivity problems
  • Chrome extension installation issues (use Chrome Web Store support)

The Claude.app vs Claude Code Conflict (Primary Issue)

Background: When Claude.app added Cowork support (browser automation from the desktop app), it introduced a competing native messaging host that conflicts with Claude Code CLI.

Two Native Hosts, Two Socket Formats

ComponentNative Host BinarySocket Location
Claude.app (Cowork)/Applications/Claude.app/Contents/Helpers/chrome-native-host/tmp/claude-mcp-browser-bridge-$USER/<PID>.sock
Claude Code CLI~/.local/share/claude/versions/<version> --chrome-native-host$TMPDIR/claude-mcp-browser-bridge-$USER (single file)

Why They Conflict

  1. Both register native messaging configs in Chrome:

    • com.anthropic.claude_browser_extension.json → Claude.app helper
    • com.anthropic.claude_code_browser_extension.json → Claude Code wrapper

  2. Chrome extension requests a native host by name

  3. If the wrong config is active, the wrong binary runs

  4. The wrong binary creates sockets in a format/location the MCP client doesn't expect

  5. Result: "Browser extension is not connected" even though everything appears to be running

The Fix: Disable Claude.app's Native Host

If you use Claude Code CLI for browser automation (not Cowork):

bash
# Disable the Claude.app native messaging configmv ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json \   ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json.disabled
# Ensure the Claude Code config exists and points to the wrappercat ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_code_browser_extension.json

If you use Cowork (Claude.app) for browser automation:

bash
# Disable the Claude Code native messaging configmv ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_code_browser_extension.json \   ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_code_browser_extension.json.disabled

You cannot use both simultaneously. Pick one and disable the other.

Toggle Script

Add this to ~/.zshrc or run directly:

bash
chrome-mcp-toggle() {    local CONFIG_DIR=~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts    local CLAUDE_APP="$CONFIG_DIR/com.anthropic.claude_browser_extension.json"    local CLAUDE_CODE="$CONFIG_DIR/com.anthropic.claude_code_browser_extension.json"
    if [[ -f "$CLAUDE_APP" && ! -f "$CLAUDE_APP.disabled" ]]; then        # Currently using Claude.app, switch to Claude Code        mv "$CLAUDE_APP" "$CLAUDE_APP.disabled"        [[ -f "$CLAUDE_CODE.disabled" ]] && mv "$CLAUDE_CODE.disabled" "$CLAUDE_CODE"        echo "Switched to Claude Code CLI"        echo "Restart Chrome and Claude Code to apply"    elif [[ -f "$CLAUDE_CODE" && ! -f "$CLAUDE_CODE.disabled" ]]; then        # Currently using Claude Code, switch to Claude.app        mv "$CLAUDE_CODE" "$CLAUDE_CODE.disabled"        [[ -f "$CLAUDE_APP.disabled" ]] && mv "$CLAUDE_APP.disabled" "$CLAUDE_APP"        echo "Switched to Claude.app (Cowork)"        echo "Restart Chrome to apply"    else        echo "Current state unclear. Check configs:"        ls -la "$CONFIG_DIR"/com.anthropic*.json* 2>/dev/null    fi}

Usage: chrome-mcp-toggle then restart Chrome (and Claude Code if switching to CLI).

Quick Diagnosis

bash
# 1. Which native host binary is running?ps aux | grep chrome-native-host | grep -v grep# Claude.app: /Applications/Claude.app/Contents/Helpers/chrome-native-host# Claude Code: ~/.local/share/claude/versions/X.X.X --chrome-native-host
# 2. Where is the socket?# For Claude Code (single file in TMPDIR):ls -la "$(getconf DARWIN_USER_TEMP_DIR)/claude-mcp-browser-bridge-$USER" 2>&1
# For Claude.app (directory with PID files):ls -la /tmp/claude-mcp-browser-bridge-$USER/ 2>&1
# 3. What's the native host connected to?lsof -U 2>&1 | grep claude-mcp-browser-bridge
# 4. Which configs are active?ls ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic*.json

Critical Insight

MCP connects at startup. If the browser bridge wasn't ready when Claude Code started, the connection will fail for the entire session. The fix is usually: ensure Chrome + extension are running with correct config, THEN restart Claude Code.

Full Reset Procedure (Claude Code CLI)

bash
# 1. Ensure correct config is activemv ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json \   ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json.disabled 2>/dev/null
# 2. Update the wrapper to use latest Claude Code versioncat > ~/.claude/chrome/chrome-native-host << 'EOF'#!/bin/bashLATEST=$(ls -t ~/.local/share/claude/versions/ 2>/dev/null | head -1)exec "$HOME/.local/share/claude/versions/$LATEST" --chrome-native-hostEOFchmod +x ~/.claude/chrome/chrome-native-host
# 3. Kill existing native host and clean socketspkill -f chrome-native-hostrm -rf /tmp/claude-mcp-browser-bridge-$USER/rm -f "$(getconf DARWIN_USER_TEMP_DIR)/claude-mcp-browser-bridge-$USER"
# 4. Restart Chromeosascript -e 'quit app "Google Chrome"' && sleep 2 && open -a "Google Chrome"
# 5. Wait for Chrome, click Claude extension icon
# 6. Verify correct native host is runningps aux | grep chrome-native-host | grep -v grep# Should show: ~/.local/share/claude/versions/X.X.X --chrome-native-host
# 7. Verify socket existsls -la "$(getconf DARWIN_USER_TEMP_DIR)/claude-mcp-browser-bridge-$USER"
# 8. Restart Claude Code

Other Common Causes

Multiple Chrome Profiles

If you have the Claude extension installed in multiple Chrome profiles, each spawns its own native host and socket. This can cause confusion.

Fix: Only enable the Claude extension in ONE Chrome profile.

Multiple Claude Code Sessions

Running multiple Claude Code instances can cause socket conflicts.

Fix: Only run one Claude Code session at a time, or use /mcp to reconnect after closing other sessions.

Hardcoded Version in Wrapper

The wrapper at ~/.claude/chrome/chrome-native-host may have a hardcoded version that becomes stale after updates.

Diagnosis:

bash
cat ~/.claude/chrome/chrome-native-host# Bad: exec "/Users/.../.local/share/claude/versions/2.0.76" --chrome-native-host# Good: Uses $(ls -t ...) to find latest

Fix: Use the dynamic version wrapper shown in the Full Reset Procedure above.

TMPDIR Not Set

Claude Code expects TMPDIR to be set to find the socket.

bash
# Checkecho $TMPDIR# Should show: /var/folders/XX/.../T/
# Fix: Add to ~/.zshrcexport TMPDIR="${TMPDIR:-$(getconf DARWIN_USER_TEMP_DIR)}"

Diagnostic Deep Dive

bash
echo "=== Native Host Binary ==="ps aux | grep chrome-native-host | grep -v grep
echo -e "\n=== Socket (Claude Code location) ==="ls -la "$(getconf DARWIN_USER_TEMP_DIR)/claude-mcp-browser-bridge-$USER" 2>&1
echo -e "\n=== Socket (Claude.app location) ==="ls -la /tmp/claude-mcp-browser-bridge-$USER/ 2>&1
echo -e "\n=== Native Host Open Files ==="pgrep -f chrome-native-host | xargs -I {} lsof -p {} 2>/dev/null | grep -E "(sock|claude-mcp)"
echo -e "\n=== Active Native Messaging Configs ==="ls ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic*.json 2>/dev/null
echo -e "\n=== Custom Wrapper Contents ==="cat ~/.claude/chrome/chrome-native-host 2>/dev/null || echo "No custom wrapper"
echo -e "\n=== TMPDIR ==="echo "TMPDIR=$TMPDIR"echo "Expected: $(getconf DARWIN_USER_TEMP_DIR)"

File Reference

FilePurpose
~/.claude/chrome/chrome-native-hostCustom wrapper script for Claude Code
/Applications/Claude.app/Contents/Helpers/chrome-native-hostClaude.app (Cowork) native host
~/.local/share/claude/versions/<version>Claude Code binary (run with --chrome-native-host)
~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.jsonConfig for Claude.app native host
~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_code_browser_extension.jsonConfig for Claude Code native host
$TMPDIR/claude-mcp-browser-bridge-$USERSocket file (Claude Code)
/tmp/claude-mcp-browser-bridge-$USER/<PID>.sockSocket files (Claude.app)

Summary

  1. Primary issue: Claude.app (Cowork) and Claude Code use different native hosts with incompatible socket formats
  2. Fix: Disable the native messaging config for whichever one you're NOT using
  3. After any fix: Must restart Chrome AND Claude Code (MCP connects at startup)
  4. One profile: Only have Claude extension in one Chrome profile
  5. One session: Only run one Claude Code instance

Original skill by @jeffzwang from @ExaAILabs. Enhanced and updated for current versions of Claude Desktop and Claude Code.

Source and attribution

Source:trailofbits/skillsinplugins/claude-in-chrome-troubleshooting/skills/chrome-mcp-troubleshootingat commit82fe822

License: No license

Content belongs to its original authors. SourceWeft indexes it from a public repository.

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