Upload Part

Last updated: 2025-12-15 10:02:19

Upload Part

Last updated: 2025-12-15 10:02:19

Overview
This API is used to upload an object to COS in multiple parts. You can upload up to 10,000 parts. The size of each part should be 1 MB to 5 GB, and the last part can be smaller than 1 MB.
Multipart Upload Process Explanation
Multipart upload requires initialization using the Initiate Multipart Upload API. After initialization, you will receive an UploadId, which uniquely identifies this upload.
When making an Upload Part request, it is necessary to carry the Key (object key), partNumber (part number), and uploadId specified during initialization, supporting out-of-order uploads.
Note:
If the uploadId and partNumber are the same, the later uploaded part will overwrite the previously uploaded part. If the object being uploaded in parts is of STANDARD_IA, MAZ_STANDARD_IA, ARCHIVE, or DEEP_ARCHIVE storage class, the overwrite operation will incur early deletion fees. For more information, please refer to Early Deletion Explanation.
If the provided uploadId does not exist, a 404 error with NoSuchUpload will be returned.
Only the root account or sub-accounts granted the permission of the Upload Part API can call this API.
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Authorization Description
In the authorization policy, set action to cos:UploadPart. View all actions.
Request
Sample request
PUT /<ObjectKey>?partNumber=PartNumber&uploadId=UploadId HTTP/1.1
Host: <BucketName-APPID>.cos.<Region>.myqcloud.com
Date: GMT Date
Content-Type: Content Type
Content-Length: Content Length
Content-MD5: MD5
Authorization: Auth String
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[Object Part]
Note: 
Host:<BucketName-APPID>.cos.<Region>.myqcloud.com, where <BucketName-APPID> is the bucket name followed by the APPID, such as examplebucket-1250000000 (see Bucket Overview > Basic Information and Bucket Overview > Bucket Naming Conventions), and <Region> is a COS region (see Regions and Access Endpoints).
Authorization: Auth String (See Request Signature for details.)
Request parameters
Parameter
Description
Type
Required
ObjectKey
Call the Initiate Multipart Upload API to initialize the specified object key (Object name). For details, see Object Overview.
string
Yes
partNumber
Part number. Value range: 1−10000
integer
Yes
uploadId
Multipart upload ID obtained from the Initiate Multipart Upload API
string
Yes
Request headers
In addition to common request headers, this API also supports the following request headers. For more information about common request headers, please see Common Request Headers.
Name
Description
Type
Required or Not
x-cos-traffic-limit
The rate-limiting value for traffic control targeting this multipart upload must be a number, with the default unit being bit/s. The speed limit setting range is 819200 - 838860800 (800Kb/s-800Mb/s). If outside of this range, it will return a 400 error.
integer
No
x-cos-psize-max
Limit the maximum size of each upload part in bytes. Uploads with part size above this value will be marked as failed.
Note:
Used in conjunction with the Complete Multipart Upload API and the x-cos-pnum-max header (to limit the maximum value of the number of chunks), it can restrict the maximum size of the file to be uploaded in parts.
integer
No
x-cos-psize-min
The minimum size of each upload part is limited to X bytes. Uploads with parts less than this size will be marked as failed.
Note:
Used in conjunction with the Complete Multipart Upload API and the x-cos-pnum-min header (to limit the minimum value of the number of chunks), it can restrict the minimum size of the file to be uploaded in parts.
integer
No
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SSE-related headers
If SSE-C is used during the initialization of the current multipart upload, you need to specify the encryption algorithm and key that were specified during the initialization. Otherwise, you cannot specify the following headers.
Field
Description
Type
Required
x-cos-server-side-encryption-customer-algorithm
Server-side encryption algorithm. Currently, only AES256 is supported.
string
Yes
x-cos-server-side-encryption-customer-key
Base64-encoded server-side encryption key. 
Example: MDEyMzQ1Njc4OUFCQ0RFRjAxMjM0NTY3ODlBQkNERUY=
string
Yes
x-cos-server-side-encryption-customer-key-MD5
Base64-encoded MD5 checksum of the server-side encryption key. 
Example: U5L61r7jcwdNvT7frmUG8g==
string
Yes
Request body
The request body of this API is the part content of the object (file).
Response
Response headers
In addition to common response headers, this API also returns the following response headers. For more information about common response headers, please see Common Response Headers.
SSE-related headers
If server-side encryption is used during the initialization of the current multipart upload, this API will return headers used specifically for server-side encryption. For more information, please see Server-Side Encryption Headers.
Response body
The response body of this API is empty.
Error codes
This API returns common error responses and error codes. For more information, see Error Codes.
Examples
Example 1: simple use case
Request
PUT /exampleobject?partNumber=1&uploadId=1585130821cbb7df1d11846c073ad648e8f33b087cec2381df437acdc833cf654b9ecc6361 HTTP/1.1
Host: examplebucket-1250000000.cos.ap-beijing.myqcloud.com
Date: Wed, 25 Mar 2020 10:07:14 GMT
Content-Type: application/octet-stream
Content-Length: 1048576
Content-MD5: OScKloo1fSQgfpkRFiUH6w==
Authorization: q-sign-algorithm=sha1&q-ak=************************************&q-sign-time=1585130834;1585138034&q-key-time=1585130834;1585138034&q-header-list=content-length;content-md5;content-type;date;host&q-url-param-list=partnumber;uploadid&q-signature=a815da18232cfec87e8218f32f31b1e2c5eb****
Connection: close
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[Object Part]
Response
HTTP/1.1 200 OK
Content-Length: 0
Connection: close
Date: Wed, 25 Mar 2020 10:07:14 GMT
ETag: "39270a968a357d24207e9911162507eb"
Server: tencent-cos
x-cos-hash-crc64ecma: 9973912126177188060
x-cos-request-id: NWU3YjJkNTJfZDBjODJhMDlfMjU4NTZfMjc5MzBh****
Sample 2: using server-side encryption SSE-COS
Request
PUT /exampleobject?partNumber=1&uploadId=1590862540251355295a5c736513d70d42b92bbde4f0fafb5e0ecb314b55aa0018cc9fa76f HTTP/1.1
Host: examplebucket-1250000000.cos.ap-beijing.myqcloud.com
Date: Sat, 30 May 2020 18:15:50 GMT
Content-Type: application/octet-stream
Content-Length: 13
Content-MD5: EI9SjrY7Zec08nrjMfX/qg==
Authorization: q-sign-algorithm=sha1&q-ak=************************************&q-sign-time=1590862550;1590869750&q-key-time=1590862550;1590869750&q-header-list=content-length;content-md5;content-type;date;host&q-url-param-list=partnumber;uploadid&q-signature=2a0085596de5861410bcc43f3d107dc9dda5****
Connection: close
﻿
[Object Part]
Response
HTTP/1.1 200 OK
Content-Length: 0
Connection: close
Date: Sat, 30 May 2020 18:15:51 GMT
ETag: "108f528eb63b65e734f27ae331f5ffaa"
Server: tencent-cos
x-cos-hash-crc64ecma: 4510578591875220731
x-cos-request-id: NWVkMmEyZDZfYjNjMjJhMDlfMmJlM18zOWI2****
x-cos-server-side-encryption: AES256
Sample 3: using server-side encryption SSE-KMS
Request
PUT /exampleobject?partNumber=1&uploadId=15908625793957d71176fa878282d266a95b79dc2aec159b4a73d1d79c80d4f931cda6ad65 HTTP/1.1
Host: examplebucket-1250000000.cos.ap-beijing.myqcloud.com
Date: Sat, 30 May 2020 18:16:29 GMT
Content-Type: application/octet-stream
Content-Length: 13
Content-MD5: EI9SjrY7Zec08nrjMfX/qg==
Authorization: q-sign-algorithm=sha1&q-ak=************************************&q-sign-time=1590862589;1590869789&q-key-time=1590862589;1590869789&q-header-list=content-length;content-md5;content-type;date;host&q-url-param-list=partnumber;uploadid&q-signature=2d1231c77c72727bd1c2454726813e095a7e****
Connection: close
﻿
[Object Part]
Response
HTTP/1.1 200 OK
Content-Length: 0
Connection: close
Date: Sat, 30 May 2020 18:16:30 GMT
ETag: "1d3e8ae9da423b440341b09f1616f074"
Server: tencent-cos
x-cos-hash-crc64ecma: 4510578591875220731
x-cos-request-id: NWVkMmEyZmRfYTRiOTJhMDlfMTE0ZGRfMmE3OTk4****
x-cos-server-side-encryption: cos/kms
x-cos-server-side-encryption-cos-kms-key-id: 48ba38aa-26c5-11ea-855c-52540085****
Example 4: using server-side encryption SSE-C
Request
PUT /exampleobject?partNumber=1&uploadId=1590862610acd643927bad05cd3947bf98b56b04b0b0b2a45a49969f87cc95b7fd5fcc065a HTTP/1.1
Host: examplebucket-1250000000.cos.ap-beijing.myqcloud.com
Date: Sat, 30 May 2020 18:17:01 GMT
x-cos-server-side-encryption-customer-algorithm: AES256
x-cos-server-side-encryption-customer-key: MDEyMzQ1Njc4OUFCQ0RFRjAxMjM0NTY3ODlBQkNERUY=
x-cos-server-side-encryption-customer-key-MD5: U5L61r7jcwdNvT7frmUG8g==
Content-Type: application/octet-stream
Content-Length: 13
Content-MD5: EI9SjrY7Zec08nrjMfX/qg==
Authorization: q-sign-algorithm=sha1&q-ak=************************************&q-sign-time=1590862621;1590869821&q-key-time=1590862621;1590869821&q-header-list=content-length;content-md5;content-type;date;host;x-cos-server-side-encryption-customer-algorithm;x-cos-server-side-encryption-customer-key;x-cos-server-side-encryption-customer-key-md5&q-url-param-list=partnumber;uploadid&q-signature=6d0914f1db0e03569b6b5d340dc8d71616bf****
Connection: close
﻿
[Object Part]
Response
HTTP/1.1 200 OK
Content-Length: 0
Connection: close
Date: Sat, 30 May 2020 18:17:01 GMT
ETag: "ff14981a35a58eb97bca838b055c573b"
Server: tencent-cos
x-cos-hash-crc64ecma: 4510578591875220731
x-cos-request-id: NWVkMmEzMWRfYjRjOTJhMDlfYWRhXzFhZmYw****
x-cos-server-side-encryption-customer-algorithm: AES256
x-cos-server-side-encryption-customer-key-MD5: U5L61r7jcwdNvT7frmUG8g==

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Parameter	Description	Type	Required
ObjectKey	Call the Initiate Multipart Upload API to initialize the specified object key (Object name). For details, see Object Overview.	string	Yes
partNumber	Part number. Value range: 1−10000	integer	Yes
uploadId	Multipart upload ID obtained from the `Initiate Multipart Upload` API	string	Yes

Name	Description	Type	Required or Not
x-cos-traffic-limit	The rate-limiting value for traffic control targeting this multipart upload must be a number, with the default unit being bit/s. The speed limit setting range is 819200 - 838860800 (800Kb/s-800Mb/s). If outside of this range, it will return a 400 error.	integer	No
x-cos-psize-max	Limit the maximum size of each upload part in bytes. Uploads with part size above this value will be marked as failed. Note: Used in conjunction with the Complete Multipart Upload API and the `x-cos-pnum-max` header (to limit the maximum value of the number of chunks), it can restrict the maximum size of the file to be uploaded in parts.	integer	No
x-cos-psize-min	The minimum size of each upload part is limited to X bytes. Uploads with parts less than this size will be marked as failed. Note: Used in conjunction with the Complete Multipart Upload API and the `x-cos-pnum-min` header (to limit the minimum value of the number of chunks), it can restrict the minimum size of the file to be uploaded in parts.	integer	No

Field	Description	Type	Required
x-cos-server-side-encryption-customer-algorithm	Server-side encryption algorithm. Currently, only `AES256` is supported.	string	Yes
x-cos-server-side-encryption-customer-key	Base64-encoded server-side encryption key. Example: `MDEyMzQ1Njc4OUFCQ0RFRjAxMjM0NTY3ODlBQkNERUY=`	string	Yes
x-cos-server-side-encryption-customer-key-MD5	Base64-encoded MD5 checksum of the server-side encryption key. Example: `U5L61r7jcwdNvT7frmUG8g==`	string	Yes

tencent cloud

Overview

Multipart Upload Process Explanation

Authorization Description

Request

Sample request

Request parameters

Request headers

Request body

Response

Response headers

Response body

Error codes

Examples

Example 1: simple use case

Request

Response

Sample 2: using server-side encryption SSE-COS

Request

Response

Sample 3: using server-side encryption SSE-KMS

Request

Response

Example 4: using server-side encryption SSE-C

Request

Response