# PATCH /v1/convai/knowledge-base/{documentation_id}/update-file (ElevenLabs API)
Base URL: https://api.elevenlabs.io
Auth: xi-api-key: <ELEVENLABS_API_KEY>
Last verified: 2026-09-03

> Update File Document

## Critical Gotchas
* Authentication uses the non-standard `xi-api-key` header, not `Authorization: Bearer`. Sending a Bearer token returns HTTP 401.
* Text-to-speech responses are raw binary audio, not JSON. Write the body to a file (`--output speech.mp3`) rather than parsing it.

## cURL
curl -X PATCH 'https://api.elevenlabs.io/v1/convai/knowledge-base/documentation-id/update-file' \
  -H "xi-api-key: $ELEVENLABS_API_KEY" \
  -F 'file=@sample.bin'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| documentation_id | path | string | Yes | The id of a document from the knowledge base. This is ret... |
| file | body | string | Yes | Documentation that the agent will have access to in order... |

## Response (200 OK)
{"id":"string","name":"string"}

---
Need an API key? Get one at https://elevenlabs.io/app/sign-up