---
title: "Soft 404: glossary: Agent Ready HTML"
description: "Soft 404 defined: A missing page that returns 200 with an error message in the body. Agents and crawlers cannot tell it from a real page."
canonical: https://agentreadyhtml.com/glossary/soft-404/
site: "Agent Ready HTML"
last_updated: 2026-11-04
section: "Glossary"
---

# Soft 404: glossary: Agent Ready HTML

> Soft 404 defined: A missing page that returns 200 with an error message in the body. Agents and crawlers cannot tell it from a real page.

Source: https://agentreadyhtml.com/glossary/soft-404/
Site: Agent Ready HTML
Last reviewed: 2026-11-04

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

## Where it shows up on this site

-   [Guide: real status codes on a SPA](https://agentreadyhtml.com/guides/real-status-codes-on-a-spa/)
-   [Soft 404s in the crawl, by platform](https://agentreadyhtml.com/soft-404s/)

## Neighbouring terms

-   [Agent 404](https://agentreadyhtml.com/glossary/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](https://agentreadyhtml.com/glossary/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](https://agentreadyhtml.com/glossary/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)](https://agentreadyhtml.com/glossary/server-side-rendering/): 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) https://developers.google.com/search/docs/crawling-indexing/javascript/javascript-seo-basics, read 4 November 2026

Last reviewed 4 November 2026

Edition

Crawl

2026-11-04

Page updated

2026-11-04

Method

How the viewer reads a page, how a file is graded and how a platform is scored: [the method page](https://agentreadyhtml.com/method/).