Versioning for the Azure Storage services

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The Microsoft Azure storage services support multiple versions. To make a request against the storage services, you must specify the version that you want to use for that operation, unless the request is anonymous.

The current version of the Azure storage services is 2021-12-02, and using that version is recommended where possible. For a list of all other supported versions, and for information about using each version, see Previous Azure Storage service versions.

The 2021-12-02 service version includes the following features:

  • The ability to set a blob's Access tier to Cold with Set Blob Tier.
  • List Directories and Files will now percent-encode (per RFC 2396) all File Name, Directory Name, Prefix or DirectoryPath element values which contain characters invalid in XML (specifically, U+FFFE or U+FFFF).
  • List Handles will now percent-encode (per RFC 2396) all Path element values which contain characters invalid in XML (specifically, U+FFFE or U+FFFF).

Specifying service versions in requests

How you specify the version of the storage services to use for a request relates to how that request is authorized. The following sections describe authorization options and how the service version is specified for each:

  • Requests using an OAuth 2.0 token from Azure Active Directory (Azure AD). To authorize a request with Azure AD, pass the x-ms-version header on the request with a service version of 2017-11-09 or higher. For more information, see Call storage operations with OAuth tokens in Authorize with Azure Active Directory.

  • Requests using Shared Key or Shared Key Lite. To authorize a request with Shared Key/Shared Key Lite, pass the x-ms-version header on the request. In the case of the Blob service, you can specify the default version for all requests by calling Set Blob Service Properties.

  • Requests using a shared access signature (SAS). You can specify two versioning options on a shared access signature. The optional api-version header indicates which service version to use to execute the API operation. The required SignedVersion (sv) parameter specifies the service version to use to authorize the request made with the SAS. If the api-version header is not specified, then the value of the SignedVersion (sv) parameter also indicates the version to use to execute the API operation.

  • Requests using anonymous access. In the case of anonymous access against the Blob service, no version is passed in; the heuristics for which version is used for the request are described below.

Requests authorized using Azure AD, Shared Key, or Shared Key Lite

To authorize a request with Azure AD, Shared Key, or Shared Key Lite, specify the x-ms-version header on the request. The x-ms-version request header value must be specified in the format YYYY-MM-DD. For example:

Request Headers:  
x-ms-version: 2020-04-08

The following rules indicate how these requests are evaluated to determine the version to use in processing the request.

  • If a request has a valid x-ms-version header, the storage service uses the specified version. All requests to the Table and Queue services that do not use a shared access signature must specify an x-ms-version header. All requests to the Blob service that do not use a shared access signature must specify an x-ms-version header unless the default version has been set, as described below.

  • If a request to the Blob service does not have an x-ms-version header, but the account owner has set a default version using Set Blob Service Properties, then the specified default version is used as the version for the request.

Requests authorized with a shared access signature

A shared access signature (SAS) generated using version 2014-02-14 or later supports two versioning options:

  • The api-version query parameter defines the REST protocol version to use for processing a request made using the SAS.

  • The SignedVersion (sv) query parameter defines the SAS version to use for authorization.

The SignedVersion query parameter is used for authorization when a client makes a request using the SAS. Authorization parameters such as si, sr, sp, sig, st, se, tn, spk, srk, epk, and erk are all interpreted using the specified version.

REST protocol parameters such as rscc, rscd, rsce, rscl, and rsct are enforced using the version provided in the api-version parameter header. If the api-version header is not specified, then the service version provided for SignedVersion is used.

The api-version parameter is not part of the string-to-sign in the authorization header, as described in Create a service SAS.

The following table explains the versioning scheme used by the service for authorization and for calling the REST protocol when the SignedVersion parameter is set to version 2014-02-14 or later.

Value of api-version parameter Version used for authorization Version used for protocol behavior
Not specified Version specified in the sv parameter Version specified in the sv parameter
Any valid storage services version in format XXXX-XX-XX Version specified in the sv parameter Valid storage services version XXXX-XX-XX

Example 1

The following sample request calls List Blobs with sv=2015-04-05, and without the api-version parameter.

https://myaccount.blob.core.windows.net/mycontainer?restype=container&comp=list&sv=2015-04-05&si=readpolicy&sig=a39 %2BYozJhGp6miujGymjRpN8tsrQfLo9Z3i8IRyIpnQ%3d

In this case, the service authenticates and authorizes the request using version 2015-04-05 and also executes the operation using version 2015-04-05.

Example 2

The following sample request calls List Blobs with sv=2015-04-05 and with the api-version parameter.

https://myaccount.blob.core.windows.net/mycontainer?restype=container&comp=list&sv=2015-04-05&si=readpolicy&sig=a39 %2BYozJhGp6miujGymjRpN8tsrQfLo9Z3i8IRyIpnQ%3d&api-version=2012-02-12

Here, the service authorizes the request using version 2015-04-05 and executes the operation using version 2012-02-12.

Note

The .NET Storage Client Library will always set the REST protocol version (in the api-version parameter) to the version that it is based on.

Requests via anonymous access

Requests made via anonymous access are handled differently depending on the type of storage account they are made against.

For general-purpose storage accounts

If an anonymous request to a general-purpose storage account does not specify the x-ms-version header, and the default version for the service has not been set using Set Blob Service Properties, then the service uses the earliest possible version to process the request. However, if the container was made public with a Set Container ACL operation performed using version 2009-09-19 or newer, then the request is processed using version 2009-09-19.

For Blob storage accounts

If an anonymous request to a Blob storage account does not specify the x-ms-version header, and the default version for the service has not been set using Set Blob Service Properties, then the service uses the earliest possible version to process the request. For a Blob storage account, the earliest possible version is 2014-02-14.

See also