GoogleChrome/lighthouse · error · LighthouseError

NO_LCP

NO_LCP

Error message

The page did not display content that qualifies as a Largest Contentful Paint (LCP). Ensure the page has a valid LCP element and then try again. ({errorCode})

What it means

Thrown as a LighthouseError with code NO_LCP when computeObservedMetric() for the standard LargestContentfulPaint metric finds that processedNavigation.timings.largestContentfulPaint is undefined. This is the primary LCP failure path: the page never produced a qualifying Largest Contentful Paint during the observed trace. Lighthouse cannot compute a timing value for the metric.

Source

Thrown at core/computed/metrics/largest-contentful-paint.js:38

class LargestContentfulPaint extends NavigationMetric {
  /**
   * @param {LH.Artifacts.NavigationMetricComputationData} data
   * @param {LH.Artifacts.ComputedContext} context
   * @return {Promise<LH.Artifacts.LanternMetric>}
   */
  static computeSimulatedMetric(data, context) {
    const metricData = NavigationMetric.getMetricComputationInput(data);
    return LanternLargestContentfulPaint.request(metricData, context);
  }

  /**
   * @param {LH.Artifacts.NavigationMetricComputationData} data
   * @return {Promise<LH.Artifacts.Metric>}
   */
  static async computeObservedMetric(data) {
    const {processedNavigation} = data;
    if (processedNavigation.timings.largestContentfulPaint === undefined) {
      throw new LighthouseError(LighthouseError.errors.NO_LCP);
    }

    return {
      timing: processedNavigation.timings.largestContentfulPaint,
      timestamp: processedNavigation.timestamps.largestContentfulPaint,
    };
  }
}

const LargestContentfulPaintComputed = makeComputedArtifact(
  LargestContentfulPaint,
  ['devtoolsLog', 'gatherContext', 'settings', 'simulator', 'trace', 'URL', 'SourceMaps', 'HostDPR']
);
export {LargestContentfulPaintComputed as LargestContentfulPaint};

View on GitHub (pinned to 9515cd4e58)

Solutions

1. Ensure the page renders at least one visible content block (text, image, video poster) above the fold
2. Use a Chrome version that supports LCP (72+) and run in a visible or new-headless window
3. If using programmatic trace collection, include 'disabled-by-default-largestContentfulPaint' in trace categories
4. Verify no JavaScript error prevents content rendering before the trace ends

// Pre-check LCP timing before requesting the metric
const processedNavigation = await ProcessedNavigation.request(trace, context);
if (processedNavigation.timings.largestContentfulPaint === undefined) {
  // No LCP — metric cannot be computed
  return { timing: undefined, notApplicable: true };
}

/** @type {(nav: LH.Artifacts.ProcessedNavigation) => nav is LH.Artifacts.ProcessedNavigation & {timings: {largestContentfulPaint: number}}} */
function hasLCP(nav) {
  return typeof nav.timings.largestContentfulPaint === 'number';
}

try {
  const lcp = await LargestContentfulPaint.request(data, context);
} catch (e) {
  if (e instanceof LighthouseError && e.code === 'NO_LCP') {
    // Page has no LCP — mark metric as not applicable
    return { notApplicable: true, reason: 'NO_LCP' };
  }
  throw e;
}

When it happens

Trigger: Running the LargestContentfulPaint computed artifact in observed mode on a trace where no LCP candidate event was emitted by the browser. The check `processedNavigation.timings.largestContentfulPaint === undefined` is true, triggering the throw.

Common situations: Pages with no visible content at load time (blank pages, login walls, JS-rendered SPAs that fail). Background tabs where paint is deferred. Traces collected with insufficient trace categories. Pages where content appears but is below the fold or in a display:none container.

Related errors

• NO_LCP
• NO_LCP_ALL_FRAMES
• NO_LCP
• NO_DCL
• NO_SCREENSHOTS

AI-assisted analysis of GoogleChrome/lighthouse@9515cd4e58 (2026-08-13). Data as JSON: /api/errors/aac2798206d52fe3. Report an issue: GitHub.