claude-in-chrome-troubleshooting

Claude in Chrome MCP Troubleshooting

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Install skill "claude-in-chrome-troubleshooting" with this command: npx skills add lv416e/dotfiles/lv416e-dotfiles-claude-in-chrome-troubleshooting

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

Component Native Host Binary Socket 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

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

Chrome extension requests a native host by name

If the wrong config is active, the wrong binary runs

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

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):

Disable the Claude.app native messaging config

mv ~/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 wrapper

cat ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_code_browser_extension.json

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

Disable the Claude Code native messaging config

mv ~/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:

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 "$CLAUDE_APP" &#x26;&#x26; ! -f "$CLAUDE_APP.disabled" ]]; then
    # Currently using Claude.app, switch to Claude Code
    mv "$CLAUDE_APP" "$CLAUDE_APP.disabled"
    [[ -f "$CLAUDE_CODE.disabled" ]] &#x26;&#x26; mv "$CLAUDE_CODE.disabled" "$CLAUDE_CODE"
    echo "Switched to Claude Code CLI"
    echo "Restart Chrome and Claude Code to apply"
elif [[ -f "$CLAUDE_CODE" &#x26;&#x26; ! -f "$CLAUDE_CODE.disabled" ]]; then
    # Currently using Claude Code, switch to Claude.app
    mv "$CLAUDE_CODE" "$CLAUDE_CODE.disabled"
    [[ -f "$CLAUDE_APP.disabled" ]] &#x26;&#x26; 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

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)

1. Ensure correct config is active

mv ~/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 version

cat > ~/.claude/chrome/chrome-native-host << 'EOF' #!/bin/bash LATEST=$(ls -t ~/.local/share/claude/versions/ 2>/dev/null | head -1) exec "$HOME/.local/share/claude/versions/$LATEST" --chrome-native-host EOF chmod +x ~/.claude/chrome/chrome-native-host

3. Kill existing native host and clean sockets

pkill -f chrome-native-host rm -rf /tmp/claude-mcp-browser-bridge-$USER/ rm -f "$(getconf DARWIN_USER_TEMP_DIR)/claude-mcp-browser-bridge-$USER"

4. Restart Chrome

osascript -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 running

ps aux | grep chrome-native-host | grep -v grep

Should show: ~/.local/share/claude/versions/X.X.X --chrome-native-host

7. Verify socket exists

ls -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:

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.

Check

echo $TMPDIR

Should show: /var/folders/XX/.../T/

Fix: Add to ~/.zshrc

export TMPDIR="${TMPDIR:-$(getconf DARWIN_USER_TEMP_DIR)}"

Diagnostic Deep Dive

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

File Purpose

~/.claude/chrome/chrome-native-host

Custom wrapper script for Claude Code

/Applications/Claude.app/Contents/Helpers/chrome-native-host

Claude.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.json

Config for Claude.app native host

~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_code_browser_extension.json

Config for Claude Code native host

$TMPDIR/claude-mcp-browser-bridge-$USER

Socket file (Claude Code)

/tmp/claude-mcp-browser-bridge-$USER/<PID>.sock

Socket files (Claude.app)

Summary

  • Primary issue: Claude.app (Cowork) and Claude Code use different native hosts with incompatible socket formats

  • Fix: Disable the native messaging config for whichever one you're NOT using

  • After any fix: Must restart Chrome AND Claude Code (MCP connects at startup)

  • One profile: Only have Claude extension in one Chrome profile

  • 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.

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