---
title: "Upload part of file"
method: PUT
path: "/files/upload_sessions/{upload_session_id}"
tags: ["Uploads (Chunked)"]
---

# Upload part of file

`PUT /files/upload_sessions/{upload_session_id}`

Uploads a chunk of a file for an upload session.

The actual endpoint URL is returned by the [`Create upload session`](https://developer.box.com/reference/post-files-upload-sessions)
and [`Get upload session`](https://developer.box.com/reference/get-files-upload-sessions-id) endpoints.

## Path parameters

- `upload_session_id` string, required

## Headers

- `digest` string, required
- `content-range` string, required

## Response `200`

Chunk has been uploaded successfully.

- UploadedPart — A chunk of a file uploaded as part of an upload session, as returned by some endpoints.
  - `part` UploadPart — The basic representation of an upload session chunk.
    - `part_id` string — The unique ID of the chunk.
    - `offset` integer — The offset of the chunk within the file in bytes. The lower bound of the position of the chunk within the file.
    - `size` integer — The size of the chunk in bytes.
    - `sha1` string — The SHA1 hash of the chunk.

## Other responses

- `409` — Returns an error if the chunk conflicts with another chunk previously uploaded.
- `412` — Returns an error if a precondition was not met.
- `416` — Returns an error if the content range does not match a specified range for the session.
- `default` — An unexpected client error.

---

[API](https://skmtc.net/box/apis/platform-api.md) · [All operations](https://skmtc.net/box/apis/platform-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/box/platform-api/versions/ba8f087e1a4d/schema)