---
title: "Fern adds llms.txt filters and wider agent 404s: Agent Ready HTML"
description: "Fern adds llms.txt filters and wider agent 404s, dated 2026-09-18, with its source and the kind of source it is. Read 2026-11-04."
canonical: https://agentreadyhtml.com/news/2026-09-18-fern-adds-llms-txt-filters-and-wider-agent-404s/
site: "Agent Ready HTML"
last_updated: 2026-11-04
date: 2026-09-18
section: "News"
---

# Fern adds llms.txt filters and wider agent 404s: Agent Ready HTML

> Fern adds llms.txt filters and wider agent 404s, dated 2026-09-18, with its source and the kind of source it is. Read 2026-11-04.

Source: https://agentreadyhtml.com/news/2026-09-18-fern-adds-llms-txt-filters-and-wider-agent-404s/
Site: Agent Ready HTML
Last reviewed: 2026-11-04

# Fern adds llms.txt filters and wider agent 404s

In short

Fern added lang=php and excludeChangelog=true to llms.txt and per-page markdown URLs, and raised the similar-page suggestions in agent 404 responses from three to five. Fern serves llms.txt at the root and for every navigation node: sections, products, versions, tabs, API references and changelogs.

Published 18 September 2026

Dated 18 September 2026. Source type: primary source. [Read the source](https://buildwithfern.com/learn/docs/changelog), read 4 November 2026.

## What it changes for a reader

-   The llms.txt reference covers the proposal, the versions and the evidence on whether agents use the file. [Open it](https://agentreadyhtml.com/llms-txt/).
-   The guide to serving markdown on request shows the rule and the headers. [Open it](https://agentreadyhtml.com/guides/serve-markdown-on-request/).
-   The guide to real status codes shows how to make a missing page answer 404. [Open it](https://agentreadyhtml.com/guides/real-status-codes-on-a-spa/).

## On this site

-   [Fern profile](https://agentreadyhtml.com/platforms/fern/)
-   [All news](https://agentreadyhtml.com/news/)
-   [Run the viewer on your own page](https://agentreadyhtml.com/viewer/)

## Sources

1.  [Fern changelog](https://buildwithfern.com/learn/docs/changelog) https://buildwithfern.com/learn/docs/changelog, 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/).