What’s Less Harmful: 301 Redirect or “404 Error Pages”?

Google’s Gary Illyes answered a question about which is less worse to use, millions of 404 error pages or 301 redirects. The question was simple:“What is less harmful: having millions of 404 error pages or millions of 301 redirects, where sold product pages redirect to the parent listing page?”The answer was also simple, although it could have gone into more detail. What’s happening is that the request for missing webpages “cannot be fulfilled.”There is an error in that the page page is not found. But the server only responds with a status code, 404 (page not found). A 404 status code does not indicate whether this lack of representation is temporary or permanent;…”Another trustworthy and authoritative HTML resource, the Mozilla Web Docs, defines the 404 status code like this:“The HTTP 404 Not Found response status code indicates that the server cannot find the requested resource.