Amazon S3 UploadPart API

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Uploads a part in a multipart upload.


In this operation, you provide part data in your request. However, you have an option to specify your existing Amazon S3 object as a data source for the part you are uploading. To upload a part from an existing object, you use the UploadPartCopy operation.

You must initiate a multipart upload (see CreateMultipartUpload) before you can upload any part. In response to your initiate request, Amazon S3 returns an upload ID, a unique identifier, that you must include in your upload part request.

Part numbers can be any number from 1 to 10,000, inclusive. A part number uniquely identifies a part and also defines its position within the object being created. If you upload a new part using the same part number that was used with a previous part, the previously uploaded part is overwritten. Each part must be at least 5 MB in size, except the last part. There is no size limit on the last part of your multipart upload.

To ensure that data is not corrupted when traversing the network, specify the Content-MD5 header in the upload part request. Amazon S3 checks the part data against the provided MD5 value. If they do not match, Amazon S3 returns an error.

Note: After you initiate multipart upload and upload one or more parts, you must either complete or abort multipart upload in order to stop getting charged for storage of the uploaded parts. Only after you either complete or abort multipart upload, Amazon S3 frees up the parts storage and stops charging you for the parts storage.

For more information on multipart uploads, go to Multipart Upload Overview in the Amazon Simple Storage Service Developer Guide .

For information on the permissions required to use the multipart upload API, go to Multipart Upload API and Permissions in the Amazon Simple Storage Service Developer Guide.

You can optionally request server-side encryption where Amazon S3 encrypts your data as it writes it to disks in its data centers and decrypts it for you when you access it. You have the option of providing your own encryption key, or you can use the AWS managed encryption keys. If you choose to provide your own encryption key, the request headers you provide in the request must match the headers you used in the request to initiate the upload by using CreateMultipartUpload. For more information, go to Using Server-Side Encryption in the Amazon Simple Storage Service Developer Guide.

Server-side encryption is supported by the S3 Multipart Upload actions. Unless you are using a customer-provided encryption key, you don't need to specify the encryption parameters in each UploadPart request. Instead, you only need to specify the server-side encryption parameters in the initial Initiate Multipart request. For more information, see CreateMultipartUpload.

If you requested server-side encryption using a customer-provided encryption key in your initiate multipart upload request, you must provide identical encryption information in each part upload using the following headers.

  • x-amz-server-side-encryption-customer-algorithm

  • x-amz-server-side-encryption-customer-key

  • x-amz-server-side-encryption-customer-key-MD5

Special Errors

    • Code: NoSuchUpload

    • Cause: The specified multipart upload does not exist. The upload ID might be invalid, or the multipart upload might have been aborted or completed.

    • HTTP Status Code: 404 Not Found

    • SOAP Fault Code Prefix: Client

Request Syntax

PUT /Key+?partNumber=PartNumber&uploadId=UploadId HTTP/1.1 Host: Content-Length: ContentLength Content-MD5: ContentMD5 x-amz-server-side-encryption-customer-algorithm: SSECustomerAlgorithm x-amz-server-side-encryption-customer-key: SSECustomerKey x-amz-server-side-encryption-customer-key-MD5: SSECustomerKeyMD5 x-amz-request-payer: RequestPayer Body

URI Request Parameters

The request uses the following URI parameters.


Name of the bucket to which the multipart upload was initiated.

Required: Yes


Size of the body in bytes. This parameter is useful when the size of the body cannot be determined automatically.


The base64-encoded 128-bit MD5 digest of the part data. This parameter is auto-populated when using the command from the CLI. This parameter is required if object lock parameters are specified.


Object key for which the multipart upload was initiated.

Length Constraints: Minimum length of 1.

Required: Yes


Part number of part being uploaded. This is a positive integer between 1 and 10,000.

Required: Yes


Upload ID identifying the multipart upload whose part is being uploaded.

Required: Yes


Confirms that the requester knows that they will be charged for the request. Bucket owners need not specify this parameter in their requests. For information about downloading objects from requester pays buckets, see Downloading Objects in Requestor Pays Buckets in the Amazon S3 Developer Guide.

Valid Values: requester


Specifies the algorithm to use to when encrypting the object (for example, AES256).


Specifies the customer-provided encryption key for Amazon S3 to use in encrypting data. This value is used to store the object and then it is discarded; Amazon S3 does not store the encryption key. The key must be appropriate for use with the algorithm specified in the x-amz-server-side-encryption-customer-algorithm header. This must be the same encryption key specified in the initiate multipart upload request.


Specifies the 128-bit MD5 digest of the encryption key according to RFC 1321. Amazon S3 uses this header for a message integrity check to ensure that the encryption key was transmitted without error.

Request Body

The request accepts the following binary data.

Response Syntax

HTTP/1.1 200 x-amz-server-side-encryption: ServerSideEncryption ETag: ETag x-amz-server-side-encryption-customer-algorithm: SSECustomerAlgorithm x-amz-server-side-encryption-customer-key-MD5: SSECustomerKeyMD5 x-amz-server-side-encryption-aws-kms-key-id: SSEKMSKeyId x-amz-request-charged: RequestCharged

Response Elements

If the action is successful, the service sends back an HTTP 200 response.

The response returns the following HTTP headers.


Entity tag for the uploaded object.


If present, indicates that the requester was successfully charged for the request.

Valid Values: requester


The server-side encryption algorithm used when storing this object in Amazon S3 (for example, AES256, aws:kms).

Valid Values: AES256 | aws:kms


If present, specifies the ID of the AWS Key Management Service (AWS KMS) symmetric customer managed customer master key (CMK) was used for the object.


If server-side encryption with a customer-provided encryption key was requested, the response will include this header confirming the encryption algorithm used.


If server-side encryption with a customer-provided encryption key was requested, the response will include this header to provide round-trip message integrity verification of the customer-provided encryption key.


Sample Request

The following PUT request uploads a part (part number 1) in a multipart upload. The request includes the upload ID that you get in response to your Initiate Multipart Upload request.

PUT /my-movie.m2ts?partNumber=1&uploadId=VCVsb2FkIElEIGZvciBlbZZpbmcncyBteS1tb3ZpZS5tMnRzIHVwbG9hZR HTTP/1.1 Host: example-bucket.s3.<Region> Date: Mon, 1 Nov 2010 20:34:56 GMT Content-Length: 10485760 Content-MD5: pUNXr/BjKK5G2UKvaRRrOA== Authorization: authorization string ***part data omitted***

Sample Response

The response includes the ETag header. You need to retain this value for use when you send the Complete Multipart Upload request.

HTTP/1.1 200 OK x-amz-id-2: Vvag1LuByRx9e6j5Onimru9pO4ZVKnJ2Qz7/C1NPcfTWAtRPfTaOFg== x-amz-request-id: 656c76696e6727732072657175657374 Date: Mon, 1 Nov 2010 20:34:56 GMT ETag: "b54357faf0632cce46e942fa68356b38" Content-Length: 0 Connection: keep-alive Server: AmazonS3