Set Blob Metadata

The Set Blob Metadata operation sets user-defined metadata for the specified blob as one or more name-value pairs.


The Set Blob Metadata request may be constructed as follows. HTTPS is recommended. Replace myaccount with the name of your storage account:

PUT Method Request URI HTTP Version HTTP/1.1

Emulated Storage Service URI

When making a request against the emulated storage service, specify the emulator hostname and Blob service port as, followed by the emulated storage account name:

PUT Method Request URI HTTP Version HTTP/1.1

For more information, see Using the Azure Storage Emulator for Development and Testing.

URI Parameters

The following additional parameters may be specified on the request URI.

Parameter Description
timeout Optional. The timeout parameter is expressed in seconds. For more information, see Setting Timeouts for Blob Service Operations.

Request Headers

The following table describes required and optional request headers.

Request Header Description
Authorization Required. Specifies the authorization scheme, account name, and signature. For more information, see Authorize requests to Azure Storage.
Date or x-ms-date Required. Specifies the Coordinated Universal Time (UTC) for the request. For more information, see Authorize requests to Azure Storage.
x-ms-version Required for all authorized requests. Specifies the version of the operation to use for this request. For more information, see Versioning for the Azure Storage Services.
x-ms-meta-name:value Optional. Sets a name-value pair for the blob.

Each call to this operation replaces all existing metadata attached to the blob. To remove all metadata from the blob, call this operation with no metadata headers.

Note that beginning with version 2009-09-19, metadata names must adhere to the naming rules for C# identifiers.
x-ms-lease-id:<ID> Required if the blob has an active lease. To perform this operation on a blob with an active lease, specify the valid lease ID for this header.
x-ms-client-request-id Optional. Provides a client-generated, opaque value with a 1 KB character limit that is recorded in the analytics logs when storage analytics logging is enabled. Using this header is highly recommended for correlating client-side activities with requests received by the server. For more information, see About Storage Analytics Logging and Azure Logging: Using Logs to Track Storage Requests.

This operation also supports the use of conditional headers to set blob metadata only if a specified condition is met. For more information, see Specifying Conditional Headers for Blob Service Operations.

Request Headers (Customer-provided encryption keys)

Beginning with version 2019-02-02, the following headers may be specified on the request to encrypt a blob with a customer-provided key. Encryption with a customer-provided key (and the corresponding set of headers) is optional. If a blob has previously been encrypted with a customer-provided key, then these headers must be included on the request to complete the write operation successfully.

Request header Description
x-ms-encryption-key Required. The Base64-encoded AES-256 encryption key.
x-ms-encryption-key-sha256 Required. The Base64-encoded SHA256 hash of the encryption key.
x-ms-encryption-algorithm: AES256 Required. Specifies the algorithm to use for encryption. The value of this header must be AES256.

Request Body



The response includes an HTTP status code and a set of response headers.

Status Code

A successful operation returns status code 200 (OK).

For information about status codes, see Status and Error Codes.

Response Headers

The response for this operation includes the following headers. The response may also include additional standard HTTP headers. All standard headers conform to the HTTP/1.1 protocol specification.

Response header Description
ETag The ETag contains a value that you can use to perform operations conditionally. See Specifying Conditional Headers for Blob Service Operations for more information. If the request version is 2011-08-18 or newer, the ETag value will be in quotes.
Last-Modified The date/time that the blob was last modified. The date format follows RFC 1123. For more information, see Representation of Date-Time Values in Headers.

Any write operation on the blob (including updates on the blob's metadata or properties) changes the last modified time of the blob.
x-ms-request-id This header uniquely identifies the request that was made and can be used for troubleshooting the request. For more information, see Troubleshooting API Operations.
x-ms-version Indicates the version of the Blob service used to execute the request. This header is returned for requests made against version 2009-09-19 and above.
Date A UTC date/time value generated by the service that indicates the time at which the response was initiated.
x-ms-request-server-encrypted: true/false Version 2015-12-11 or newer. The value of this header is set to true if the contents of the request are successfully encrypted using the specified algorithm, and false otherwise.
x-ms-encryption-key-sha256 Version 2019-02-02 or newer. This header is returned if the request used a customer-provided key for encryption, so the client can ensure the contents of the request are successfully encrypted using the provided key.
x-ms-client-request-id This header can be used to troubleshoot requests and corresponding responses. The value of this header is equal to the value of the x-ms-client-request-id header if it is present in the request and the value is at most 1024 visible ASCII characters. If the x-ms-client-request-id header is not present in the request, this header will not be present in the response.

Response Body



This operation can be called by the account owner and by anyone with a Shared Access Signature that has permission to write to this blob or its container.


If the blob has an active lease, the client must specify a valid lease ID on the request in order to write metadata to the blob. If the client does not specify a lease ID, or specifies an invalid lease ID, the Blob service returns status code 412 (Precondition Failed). If the client specifies a lease ID but the blob does not have an active lease, the Blob service also returns status code 412 (Precondition Failed).

See Also

Authorize requests to Azure Storage
Status and Error Codes
Blob Service Error Codes