4xx client error

What this means

The URL returned a 4xx status. A 404 is reported as critical because links pointing at it are broken; 403 and 429 are reported lower because they usually mean bot protection or rate limiting rejected the crawler rather than that the page is broken.

How to fix it

For a 404, redirect to the closest live page or restore the content. For 403 and 429, confirm the page loads in a browser, then allowlist or slow the crawler and check search-engine bots are not blocked by the same rule.

Fix effort

This check needs a developer fix: it turns on a routing, hosting or infrastructure decision that no automatic edit can make safely.

Authoritative source

https://developers.google.com/search/docs/crawling-indexing/http-network-errors