Guides

Debugging Lighthouse Scans

Copy for LLMs

Scan not working? Here's how to figure out why.

Start Here: Debug Logs

90% of issues become obvious with debug logging:

unlighthouse --site example.com --debug

This shows you:

  • What URLs are being discovered
  • Which pages are being scanned
  • Any errors or timeouts
  • Chrome connection status

Watch the Browser

Can't tell what's happening? Watch it:

export default defineUnlighthouseConfig({
  puppeteerOptions: {
    headless: false, // Show the browser window
    slowMo: 250, // Slow down so you can see what's happening
    devtools: true, // Open Chrome DevTools
  },
  puppeteerClusterOptions: {
    maxConcurrency: 1, // One page at a time
  },
})

Now you'll see exactly what Unlighthouse sees—useful for:

  • Auth issues (is login working?)
  • JavaScript errors (check the console)
  • Missing content (is the page rendering?)
  • Blocked requests (check Network tab)
Visual mode is slow. Only use it to diagnose specific problems.

Common Issues

Pages Timing Out

Your site might be slow or have heavy JavaScript:

export default defineUnlighthouseConfig({
  lighthouseOptions: {
    maxWaitForLoad: 60000, // Wait up to 60s (default: 45s)
  },
})

SPA Not Rendering

JavaScript apps need time to hydrate:

export default defineUnlighthouseConfig({
  scanner: {
    skipJavascript: false, // Wait for JS to execute
  },
  lighthouseOptions: {
    maxWaitForLoad: 45000,
  },
})

SSL/Certificate Errors

On localhost or staging with self-signed certs:

export default defineUnlighthouseConfig({
  puppeteerOptions: {
    ignoreHTTPSErrors: true,
    args: ['--ignore-certificate-errors'],
  },
})

Chrome Won't Start

Try using bundled Chromium instead of system Chrome:

export default defineUnlighthouseConfig({
  chrome: {
    useSystem: false, // Download and use bundled Chromium
  },
})

Or point to a specific Chrome:

puppeteerOptions: {
  executablePath: '/usr/bin/google-chrome-stable',
}

Failed Network Requests

Log all failed requests to find what's breaking:

export default defineUnlighthouseConfig({
  hooks: {
    'puppeteer:before-goto': async (page) => {
      page.on('requestfailed', (req) => {
        console.log('❌ Failed:', req.url(), req.failure()?.errorText)
      })
    },
  },
})

Still Stuck?

  1. Check Common Errors for known issues
  2. Search GitHub Issues
  3. Ask on Discord with your debug logs
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Configuration

Configure Unlighthouse for your specific needs using configuration files and inline options.

Authentication

Scan password-protected websites with Unlighthouse. Configure basic auth, cookies, headers, localStorage, and programmatic login flows.