---
title: "Upload chunk {index} (0-based) as application/octet-stream; ?sha256= verifies it. Idempotent"
method: PUT
path: "/migrations/{migrationId}/artifacts/{artifactId}/chunks/{index}"
tags: ["Migrations"]
---

# Upload chunk {index} (0-based) as application/octet-stream; ?sha256= verifies it. Idempotent

`PUT /migrations/{migrationId}/artifacts/{artifactId}/chunks/{index}`

## Request

- Base URL: `https://hostingsurge.com/api/v1`
- URL: `https://hostingsurge.com/api/v1/migrations/{migrationId}/artifacts/{artifactId}/chunks/{index}`
- Auth: one of:
  - HTTP bearer
  - API key in cookie `__Host-hs_session`

## Path parameters

- `migrationId` string, uuid, required
- `artifactId` string, uuid, required
- `index` integer, nullable

## Query parameters

- `sha256` string

## Response `200`

Chunk stored

- object
  - `id` string, uuid, required
  - `name` string, required
  - `role` 'backup' | 'database' | 'wp-content' | 'files' | 'other', required
  - `status` 'uploading' | 'complete' | 'failed' | 'deleted', required
  - `size` integer, required
  - `receivedBytes` integer, required
  - `chunkSize` integer, required
  - `totalChunks` integer, required
  - `missingChunks` integer[], required: chunk indexes still to upload (max 1000 listed)
  - `sha256` string, nullable, required: verified checksum once complete
  - `createdAt` string, required: ISO-8601 timestamp
  - `expiresAt` string, required: ISO-8601 timestamp

## Other responses

- `400`: Invalid request (code invalid_request)
- `401`: Missing or invalid session/token (code unauthorized)
- `403`: Authenticated but not permitted (code forbidden)
- `404`: Not found or not visible to the caller (code not_found)
- `409`: Conflicting state (code conflict)
- `413`: Chunk too large
- `429`: Too many requests (code rate_limited); see Retry-After
- `501`: Not available on this server (code not_configured)
- `503`: Hosting engine unavailable (code provider_unavailable)

---

[API](https://skmtc.dev/hostingsurge/apis/hostingsurge-platform-api.md) · [All operations](https://skmtc.dev/hostingsurge/apis/hostingsurge-platform-api/llms.txt) · [OpenAPI document](https://skmtc.dev/hostingsurge/apis/hostingsurge-platform-api/revisions/4d08337cdff1?raw)