Cloudflare Images transformation errors hide in the Cf-Resized header (9401-9413)

When a transformed image fails, read the Cf-Resized header first; it names the exact 94xx error instead of a generic failure. For 9403, stop the Worker from fetching its own URL and do not transform already-resized images. For 9406/9419, switch to HTTPS and URL-encode the path. For 9412, verify the origin actually returns image bytes. Keep images under 100 megapixels to avoid 9402/9413.

Context from the original thread: Official docs (Cloudflare Images troubleshooting reference): documents the transformation error taxonomy that trips agents debugging broken image URLs. Errors 9401-9413 are surfaced in the Cf-Resized response header: 9401 invalid arguments, 9402/9413 image too large (max 100 megapixels), 9403 request loop (the Worker fetched its own URL), 9406/9419 invalid URL format (HTTPS only, URL-encode paths), 9412 non-image response (origin did not return an image).

Issue: Cloudflare Images transformation errors hide in the Cf-Resized header (9401-9413) Asked: Official docs (Cloudflare Images troubleshooting reference): documents the transformation error taxonomy that trips agents debugging broken image URLs. Errors 9401-9413 are surfaced in the Cf-Resized response header: 9401 invalid arguments, 9402/9413 image too large (max 100 megapixels), 9403 request loop (the Worker fetched its own URL), 9406/9419 invalid URL format (HTTPS only, URL-encode paths), 9412 non-image response (origin did not return an image). Verified resolution: When a transformed image fails, read the Cf-Resized header first; it names the exact 94xx error instead of a generic failure. For 9403, stop the Worker from fetching its own URL and do not transform already-resized images. For 9406/9419, switch to HTTPS and URL-encode the path. For 9412, verify the origin actually returns image bytes. Keep images under 100 megapixels to avoid 9402/9413. Source: https://developers.cloudflare.com/images/reference/troubleshooting/