> ## Documentation Index > Fetch the complete documentation index at: https://docs.ndi.nace.ai/llms.txt > Use this file to discover all available pages before exploring further. # upload_session_part > Upload one part of a chunked upload. Cost class: **fast**. Exempt from the tenant's per-minute rate limit (unlike every other upload-session route): a multi-GB file at ``chunk_size`` is already dozens of requests, and each part is bounded and byte-for-byte revalidated at ``complete`` anyway, so RPM protection would only add friction here without protecting anything. Idempotent: re-PUTing the same ``part_number`` overwrites it, so a retried part after a dropped connection is always safe. ## OpenAPI ````yaml /openapi.json put /v1/workspaces/{workspace_id}/upload-sessions/{session_id}/parts/{part_number} openapi: 3.1.0 info: description: >- Document intelligence: parse, split, classify, extract, and ground files, or build a searchable workspace. Authenticate with ``X-API-Key``. title: NDI Platform API version: 0.1.0 servers: - url: https://ndi-api.nace.ai security: [] tags: [] paths: /v1/workspaces/{workspace_id}/upload-sessions/{session_id}/parts/{part_number}: put: tags: - files summary: upload_session_part description: |- Upload one part of a chunked upload. Cost class: **fast**. Exempt from the tenant's per-minute rate limit (unlike every other upload-session route): a multi-GB file at ``chunk_size`` is already dozens of requests, and each part is bounded and byte-for-byte revalidated at ``complete`` anyway, so RPM protection would only add friction here without protecting anything. Idempotent: re-PUTing the same ``part_number`` overwrites it, so a retried part after a dropped connection is always safe. operationId: >- upload_session_part_v1_workspaces__workspace_id__upload_sessions__session_id__parts__part_number__put parameters: - description: 0-based part index. in: path name: part_number required: true schema: description: 0-based part index. minimum: 0 title: Part Number type: integer - description: Workspace identifier. in: path name: workspace_id required: true schema: description: Workspace identifier. format: uuid title: Workspace Id type: string - description: Upload session identifier. in: path name: session_id required: true schema: description: Upload session identifier. format: uuid title: Session Id type: string responses: '200': content: application/json: schema: $ref: '#/components/schemas/UploadSessionPartResponse' description: Successful Response '504': content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' description: Gateway Timeout default: content: application/json: example: error: code: invalid_request detail: null message: >- Request body has extra fields that this operation does not accept. request_id: req-01j9k2n3p4q5r6s7t8v9 retryable: false schema: $ref: '#/components/schemas/ErrorEnvelope' description: >- Typed error envelope used by every 4xx and 5xx. ``error.code`` distinguishes the failure; HTTP status is a consequence of the code. security: - UploadSessionTokenHeader: [] components: schemas: UploadSessionPartResponse: additionalProperties: false description: Result of ``PUT .../upload-sessions/{session_id}/parts/{part_number}``. properties: part_number: title: Part Number type: integer size_bytes: description: Bytes actually received for this part. title: Size Bytes type: integer required: - part_number - size_bytes title: UploadSessionPartResponse type: object ErrorEnvelope: description: Every non-2xx body on ``/v1``. example: error: code: invalid_request detail: null message: Request body has extra fields that this operation does not accept. request_id: req-01j9k2n3p4q5r6s7t8v9 retryable: false properties: error: $ref: '#/components/schemas/Error' required: - error title: ErrorEnvelope type: object Error: description: The error object, per spec 12 §1.8. properties: code: $ref: '#/components/schemas/ErrorCode' detail: anyOf: - additionalProperties: true type: object - type: 'null' description: Structured payload, when the code carries one. title: Detail message: description: Human- and model-readable; says what to do differently. title: Message type: string request_id: description: Per-request correlation id; matches the ``X-Request-Id`` header. title: Request Id type: string retryable: description: Whether retrying the identical request could succeed. title: Retryable type: boolean required: - code - message - retryable - request_id title: Error type: object ErrorCode: description: |- Every error the ``/v1`` surface can return. Clients must treat this as an **open** enum: a new member is an additive change (spec 12 §9), and a client that crashes on an unknown code makes every future error a breaking change. enum: - invalid_request - unsupported_file_type - file_too_large - invalid_schema - invalid_sql - invalid_path_prefix - command_not_permitted - batch_too_large - domain_validation_failed - default_label_required - wait_required_for_zero_retention - workspace_not_found - file_not_found - job_not_found - upload_not_found - node_not_found - schema_not_found - domain_not_found - session_not_found - access_label_not_found - path_conflict - schema_version_conflict - access_label_name_taken - workspace_name_taken - access_label_in_use - upload_expired - file_not_ingested - workspace_deleting - workspace_not_deletable - ingestion_in_progress - job_not_cancellable - confirmation_required - domain_not_published - domain_in_use - reserved_domain_slug - kg_not_built - kg_build_in_progress - session_busy - range_not_satisfiable - result_expired - access_denied - access_backstop_violation - access_mode_not_implemented - rate_limited - concurrency_limit_reached - quota_exceeded - corrupt_file - zero_byte_file - encrypted_file - parse_failed - ocr_failed - conversion_failed - sheetless_workbook - unplayable_media - unclassified_pages - job_cancelled - job_timeout - upstream_unavailable - internal_error - unauthorized - not_implemented title: ErrorCode type: string securitySchemes: UploadSessionTokenHeader: description: Session token from POST /v1/workspaces/{workspace_id}/upload-sessions. in: header name: X-Upload-Token type: apiKey ````