Browser troubleshooting

Problem: "Failed to start Chrome CDP on port 18800"

OpenClaw's browser control server fails to launch Chrome/Brave/Edge/Chromium with the error:

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

Root cause

On Ubuntu (and many Linux distros), the default Chromium installation is a snap package. Snap's AppArmor confinement interferes with how OpenClaw spawns and monitors the browser process.

The apt install chromium command installs a stub package that redirects to snap:

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

This is NOT a real browser - it's just a wrapper.

Other common Linux launch failures:

• The profile appears to be in use by another Chromium process means Chrome found stale Singleton* lock files in the managed profile directory. OpenClaw removes those locks and retries once when the lock points at a dead or different-host process.
• Missing X server or $DISPLAY means a visible browser was explicitly requested on a host without a desktop session. By default, local managed profiles now fall back to headless mode on Linux when DISPLAY and WAYLAND_DISPLAY are both 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 in a real desktop session.

Solution 1: Install Google Chrome (Recommended)

Install the official Google Chrome .deb package, which is not sandboxed by snap:

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

Then update your OpenClaw config (~/.openclaw/openclaw.json):

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

Solution 2: Use Snap Chromium with Attach-Only Mode

If you must use snap Chromium, configure OpenClaw to attach to a manually-started browser:

1. Update config:

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

2. 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 &

3. Optionally create a systemd user service to auto-start Chrome:

# ~/.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

Enable with: systemctl --user enable --now openclaw-browser.service

Verifying the Browser Works

Check status:

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

Test browsing:

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, raise browser.localLaunchTimeoutMs when Chrome needs more time to expose its CDP HTTP endpoint. Raise browser.localCdpReadyTimeoutMs when launch succeeds but openclaw browser start still reports not reachable after start. Values must be positive integers up to 120000 ms; invalid config values are rejected.

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

You're using an existing-session / Chrome MCP profile. OpenClaw can see local Chrome, but there are no open tabs available to attach to.

Fix options:

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

Notes:

• user is host-only. For Linux servers, containers, or remote hosts, prefer CDP profiles.
• user / other existing-session profiles keep the current Chrome MCP limits: ref-driven actions, one-file upload hooks, no dialog timeout overrides, no wait --load networkidle, and no responsebody, PDF export, download interception, or batch actions.
• Local openclaw profiles auto-assign cdpPort/cdpUrl; only set those 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