GoogleChrome/lighthouse · error · LighthouseError

NOT_HTML

NOT_HTML

Error message

The page provided is not HTML (served as MIME type {mimeType}).

What it means

Error "The page provided is not HTML (served as MIME type {mimeType})." thrown in GoogleChrome/lighthouse.

Source

Thrown at core/lib/lh-error.js:356

    message: UIStrings.pageLoadFailedInsecure,
    lhrRuntimeError: true,
  },
  /* Used when any Chrome interstitial error prevents page load.
   */
  CHROME_INTERSTITIAL_ERROR: {
    code: 'CHROME_INTERSTITIAL_ERROR',
    message: UIStrings.pageLoadFailedInterstitial,
    lhrRuntimeError: true,
  },
  /* Used when the page stopped responding and did not finish loading. */
  PAGE_HUNG: {
    code: 'PAGE_HUNG',
    message: UIStrings.pageLoadFailedHung,
    lhrRuntimeError: true,
  },
  /* Used when the page is non-HTML. */
  NOT_HTML: {
    code: 'NOT_HTML',
    message: UIStrings.notHtml,
    lhrRuntimeError: true,
  },

  // Protocol internal failures
  TRACING_ALREADY_STARTED: {
    code: 'TRACING_ALREADY_STARTED',
    message: UIStrings.internalChromeError,
    pattern: /Tracing.*started/,
    lhrRuntimeError: true,
  },
  PARSING_PROBLEM: {
    code: 'PARSING_PROBLEM',
    message: UIStrings.internalChromeError,
    pattern: /Parsing problem/,
    lhrRuntimeError: true,
  },
  READ_FAILED: {

View on GitHub (pinned to 9515cd4e58)

Solutions

1. Point Lighthouse at a page served with a text/html MIME type.
2. Check the server's Content-Type header for the URL and correct the server configuration.
3. Make sure the URL returns an HTML document, not JSON, an image, or a download.

When it happens

Trigger: Raised when the requested URL is served with a non-HTML MIME type.

Common situations: See trigger scenarios.

AI-assisted analysis of GoogleChrome/lighthouse@9515cd4e58 (2026-08-13). Data as JSON: /api/errors/e5025a3a28f947f6. Report an issue: GitHub.