Browser Troubleshooting (Linux)

Problem: “Failed to start Chrome CDP on port 18800”

Fased’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 \"fased\"."}

Root Cause

On Ubuntu and many Linux distros, the default Chromium installation is a snap package. Snap’s AppArmor confinement interferes with how Fased 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.

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 Fased config (~/.fased/fased.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 Fased to attach to a manually-started browser:

Update config:

{
  "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/.fased/browser/fased/user-data \
  about:blank &

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

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

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

[Install]
WantedBy=default.target

Enable with: systemctl --user enable --now fased-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

browser.enabled: enable browser control. Default: true.
browser.executablePath: path to a Chromium-based browser binary, such as Chrome, Brave, Edge, or Chromium. Default: auto-detected.
browser.headless: run without GUI. Default: false.
browser.noSandbox: add --no-sandbox for Linux setups that need it. Default: false.
browser.attachOnly: attach to an existing browser instead of launching one. Default: false.
browser.cdpPort: Chrome DevTools Protocol port. Default: 18800.

Problem: “Chrome extension relay is running, but no tab is connected”

You’re using the chrome profile (extension relay). It expects the Fased browser extension to be attached to a live tab. Fix options:

Use the managed browser: fased browser start --browser-profile fased (or set browser.defaultProfile: "fased").
Use the extension relay: install the extension, open a tab, and click the browser relay extension icon to attach it.

Notes:

The chrome profile uses your system default Chromium browser when possible.
Local fased profiles auto-assign cdpPort/cdpUrl; only set those for remote CDP.

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Browser Troubleshooting

Browser Troubleshooting (Linux)

Problem: “Failed to start Chrome CDP on port 18800”

Root Cause

Solution 1: Install Google Chrome (Recommended)

Solution 2: Use Snap Chromium with Attach-Only Mode

Verifying the Browser Works

Config Reference

Problem: “Chrome extension relay is running, but no tab is connected”

​Browser Troubleshooting (Linux)

​Problem: “Failed to start Chrome CDP on port 18800”

​Root Cause

​Solution 1: Install Google Chrome (Recommended)

​Solution 2: Use Snap Chromium with Attach-Only Mode

​Verifying the Browser Works

​Config Reference

​Problem: “Chrome extension relay is running, but no tab is connected”

Browser Troubleshooting (Linux)

Problem: “Failed to start Chrome CDP on port 18800”

Root Cause

Solution 1: Install Google Chrome (Recommended)

Solution 2: Use Snap Chromium with Attach-Only Mode

Verifying the Browser Works

Config Reference

Problem: “Chrome extension relay is running, but no tab is connected”