Agent Ready HTML

Soft 404

In short

A missing page that returns 200 with an error message in the body. Agents and crawlers cannot tell it from a real page. Example: Google documents strategies to avoid soft 404 errors in single-page apps. Related terms: Agent 404, Real status code, Subpath llms.txt, Server-side rendering (SSR).

Source of the example

The example in the summary above is from developers.google.com, read 4 November 2026.

Where it shows up on this site

Neighbouring terms

  • Agent 404: A 404 response written for agents, often markdown, that links the index and similar pages so the agent can recover.
  • Real status code: An HTTP status that matches what happened: 200 for a page, 404 for a missing path, 429 for throttling.
  • Subpath llms.txt: An llms.txt below the root that covers the pages under its path; v2 says the most specific file applies.
  • Server-side rendering (SSR): Rendering a page to HTML on the server per request, so the response carries the content.

Sources

  1. developers.google.com https://developers.google.com/search/docs/crawling-indexing/javascript/javascript-seo-basics, read 4 November 2026

Last reviewed 4 November 2026