Fix Chrome CDP startup issues on Linux for OpenClaw

Problem: Failed to start Chrome CDP on port 18800

{ "error": "Error: Failed to start Chrome CDP on port 18800 for profile \"openclaw\"." }

Root cause

On Ubuntu and most Linux distributions, apt install chromium installs a snap wrapper rather than a real browser:

Note, selecting 'chromium-browser' instead of 'chromium'
chromium-browser is already the newest version (2:1snap1-0ubuntu2).

Snap's AppArmor confinement blocks OpenClaw from spawning and monitoring the browser process properly.

Other common reasons Linux launches fail:

• The profile appears to be in use by another Chromium process: stale Singleton* lock files inside the managed profile directory. OpenClaw removes those locks and retries once when the lock points to a dead process or one on a different host.
• Missing X server or $DISPLAY: a visible browser was explicitly requested on a machine without a desktop session. Local managed profiles fall back to headless mode on Linux when both DISPLAY and WAYLAND_DISPLAY are unset. If you set OPENCLAW_BROWSER_HEADLESS=0, browser.headless: false, or browser.profiles.<name>.headless: false, remove that headed override, set OPENCLAW_BROWSER_HEADLESS=1, start Xvfb, run openclaw browser start --headless for a one-shot managed launch, or run OpenClaw inside a real desktop session.

Solution 1: install Google Chrome (recommended)

wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
sudo dpkg -i google-chrome-stable_current_amd64.deb
sudo apt --fix-broken install -y  # if there are dependency errors

Update ~/.openclaw/openclaw.json:

{
  "browser": {
    "enabled": true,
    "executablePath": "/usr/bin/google-chrome-stable",
    "headless": true,
    "noSandbox": true
  }
}

Solution 2: use snap Chromium in attach-only mode

If you need to keep snap Chromium, configure OpenClaw to attach to a manually started browser instead of launching it:

{
  "browser": {
    "enabled": true,
    "attachOnly": true,
    "headless": true,
    "noSandbox": true
  }
}

Start Chromium manually:

chromium-browser --headless --no-sandbox --disable-gpu \
  --remote-debugging-port=18800 \
  --user-data-dir=$HOME/.openclaw/browser/openclaw/user-data \
  about:blank &

Optionally auto-start it with a systemd user service:

# ~/.config/systemd/user/openclaw-browser.service
[Unit]
Description=OpenClaw Browser (Chrome CDP)
After=network.target

[Service]
ExecStart=/snap/bin/chromium --headless --no-sandbox --disable-gpu --remote-debugging-port=18800 --user-data-dir=%h/.openclaw/browser/openclaw/user-data about:blank
Restart=on-failure
RestartSec=5

[Install]
WantedBy=default.target

systemctl --user enable --now openclaw-browser.service

Verify the browser works

curl -s http://127.0.0.1:18791/ | jq '{running, pid, chosenBrowser}'
curl -s -X POST http://127.0.0.1:18791/start
curl -s http://127.0.0.1:18791/tabs

Config reference

On Raspberry Pi, older VPS hosts, or slow storage, use a manually launched browser with attachOnly when Chrome needs more time to expose its CDP HTTP endpoint or become ready than the managed-browser deadline allows.

Problem: No Chrome tabs found for profile="user"

You are using the user (existing-session / Chrome MCP) profile and no tabs are open to attach to.

Fix options:

1. Use the managed browser instead: openclaw browser --browser-profile openclaw start (or set browser.defaultProfile: "openclaw").
2. Keep local Chrome running with at least one open tab, then retry with --browser-profile user.

Notes:

• user is host-only. On Linux servers, containers, or remote hosts, prefer CDP profiles instead.
• user and other existing-session profiles share the current Chrome MCP limits: ref-driven actions only, one file per upload, no dialog timeoutMs overrides, no wait --load networkidle, and no responsebody, PDF export, download interception, or batch actions.
• Local openclaw-driver profiles auto-assign cdpPort/cdpUrl; only set those manually for remote CDP.
• Remote CDP profiles accept http://, https://, ws://, and wss://. Use HTTP(S) for /json/version discovery, or WS(S) when your browser service gives you a direct DevTools socket URL.

Related

• Browser
• Browser login
• Browser WSL2 troubleshooting