vercel/next.js · error · ImageError

"url" parameter is valid but upstream response is invalid

Error message

"url" parameter is valid but upstream response is invalid

What it means

Redirect-loop guard in fetchExternalImage: the upstream response was a redirect whose Location could still be parsed, but the redirect budget (count) was exhausted — too many redirects. Continuing would loop forever, so the optimizer gives up and throws ImageError 508 declaring the upstream response invalid.

Solutions

1. Verify the upstream URL returns a valid image response (correct status and content-type).

When it happens

Trigger: The upstream image response is not valid.

Common situations: The remote server returns a non-200 status or bad content for an optimized image.

AI-assisted analysis of vercel/next.js@996f957c06 (2026-08-19). Data as JSON: /api/errors/414b32026165ec7a. Report an issue: GitHub.

Appendix: source

Thrown at packages/next/src/server/image-optimizer.ts:575

    if (err.name === 'TimeoutError') {
      Log.error('upstream image response timed out for', href)
      throw new ImageError(
        504,
        '"url" parameter is valid but upstream response timed out'
      )
    }
    throw err
  }

  const locationHeader = res.headers.get('Location')
  if (
    isRedirect(res.status) &&
    locationHeader &&
    URL.canParse(locationHeader, href)
  ) {
    if (count === 0) {
      Log.error('upstream image response had too many redirects', href)
      throw new ImageError(
        508,
        '"url" parameter is valid but upstream response is invalid'
      )
    }
    const redirect = new URL(locationHeader, href).href
    return fetchExternalImage(
      redirect,
      dangerouslyAllowLocalIP,
      maximumResponseBody,
      count - 1
    )
  }

  if (!res.ok) {
    Log.error('upstream image response failed for', href, res.status)
    throw new ImageError(
      res.status,
      '"url" parameter is valid but upstream response is invalid'

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