Regtransfers/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

• mcpclaude-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

1. Both register native messaging configs in Chrome:

• com.anthropic.claudebrowserextension.json → Claude.app helper
• com.anthropic.claudecodebrowser_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):

# 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 "$CLAUDE_APP" && ! -f "$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

# 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.claudebrowserextension.json; Config for Claude.app native host ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claudecodebrowser_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

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.

@ Limitations

• Use this skill only when the task clearly matches the scope described above.
• never treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.