---
title: "Soft 404 defined | Agent Ready Checklist"
description: "Soft 404: A missing page answered with 200 and an error-looking body. Agents cannot tell it from a live page, so AR-READ-02 forbids it."
canonical: https://agentreadychecklist.com/glossary/soft-404
site: "Agent Ready Checklist"
last_updated: 2026-11-05
section: "Glossary"
---

# Soft 404 defined | Agent Ready Checklist

> Soft 404: A missing page answered with 200 and an error-looking body. Agents cannot tell it from a live page, so AR-READ-02 forbids it.

Source: https://agentreadychecklist.com/glossary/soft-404
Site: Agent Ready Checklist
Last reviewed: 2026-11-05
Agent endpoints: https://agentreadychecklist.com/llms.txt (index), https://agentreadychecklist.com/openapi.json (API), https://agentreadychecklist.com/mcp (MCP server), https://agentreadychecklist.com/ask (search)
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# Soft 404

A missing page answered with 200 and an error-looking body. Agents cannot tell it from a live page, so AR-READ-02 forbids it. Example: curl -s -o /dev/null -w "%{http\_code}" https://example.com/nope # want 404, not 200. Related row: AR-READ-02 (Real HTTP status codes). The guide "One-day agent-readiness sprint" covers a row that names Soft 404.

## Definition

A missing page answered with 200 and an error-looking body. Agents cannot tell it from a live page, so AR-READ-02 forbids it.

## Example

```bash
curl -s -o /dev/null -w "%{http_code}" https://example.com/nope   # want 404, not 200
```

## Where it appears on the checklist

-   [AR-READ-02](https://agentreadychecklist.com/checklist/ar-read-02/)Real HTTP status codes: Return accurate HTTP status codes: 404 or a real redirect for missing paths, 429 with Retry-After when throttling; never 200 for a missing page and never a silent challenge page in place of 429.
-   [Guide](https://agentreadychecklist.com/guides/one-day-agent-readiness-sprint/)The one-day agent-readiness sprint
-   [Guide](https://agentreadychecklist.com/guides/read-server-logs-for-agent-user-agents/)How to read your server logs for agent user agents
-   [Guide](https://agentreadychecklist.com/guides/keep-a-site-agent-ready-in-ci/)How to keep a site agent ready in CI

## Asked about it

### What status code should a missing page return?

A 404, or a redirect to a real replacement. Never 200 with an error body: agents cannot tell a soft 404 from a live page. Check with curl -s -o /dev/null -w "%{http\_code}" on a random path.

## Sources

-   [vercel.com/kb/guide/make-your-site-readable-by-ai-agents](https://vercel.com/kb/guide/make-your-site-readable-by-ai-agents)read 2026-11-04
-   [github.com/agentready-org/standard/blob/main/spec/spec.md](https://github.com/agentready-org/standard/blob/main/spec/spec.md)read 2026-11-04

Last reviewed 2026-11-05. AgentReady v2.0, read 2026-11-04.