llms.txt does not follow the expected format

This warning appears when your llms.txt file exists but doesn't follow the one mandatory requirement of its specification: starting with an H1 title.

What this error means

The llms.txt standard (see llmstxt.org) leaves a lot of structure optional: the summary, the sections, and the links are all optional. But it requires one minimum thing so that any reader, human or AI agent, can immediately tell what site it belongs to: the first line with content must be an H1 heading — a hash followed by a space and the site's name (for example, "# My Company"). We checked and your llms.txt file responds correctly (status 200, with content), but its first line doesn't follow that format: the hash is missing, the space after it is missing, or the file starts directly with a different kind of content, like an H2 section or free text. This doesn't mean the file is useless, but an AI agent expecting the standard format may fail to correctly parse the rest of its content, or discard it outright for not recognizing it as a valid llms.txt.

Why it matters to fix it

The wrong format doesn't block access to the file, but it can cause it to be ignored or misread.

Risk of the file being ignored

Some AI agents validate the structure before processing the content; if they don't recognize the initial H1, they may discard the whole file.

Losing the benefit of a quick summary

All the effort of structuring your llms.txt loses its value if the format isn't parsed as expected.

A sign the file wasn't built to spec

A malformed H1 usually means the file was created by hand or with a tool that doesn't strictly follow the standard, which can also affect the rest of its structure.

How to fix it step by step

Fixing this is as simple as correcting the file's first line.

Step 1

Open your llms.txt file

Access the current content of the file published on your domain.

Where to apply it: https://yourdomain.com/llms.txt.

Step 2

Fix the first line with content

Make sure it's exactly a hash, a space, and your site's name, with nothing before it.

Where to apply it: First non-blank line of the file.

Step 3

Leave the rest of the structure as is

The summary, H2 sections, and links are optional and don't need changes if you already had them.

Where to apply it: Rest of the llms.txt file.

If you want to understand it even better

To help you better understand this type of error and why it happens, we include additional materials that expand the explanations, guide with examples, or show alternative methods.

llmstxt.org

Official specification for the llms.txt format.

View resource

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