# Protocol support changes for AWS service clients
<a name="service-protocol-updates"></a>

AWS SDKs handle the wire protocols used to serialize requests and deserialize responses when communicating with AWS services. If your SDK client supports the change, your application automatically uses the updated protocol without code changes. A protocol support change does not change the modeled service API. However, applications and infrastructure that depend on a specific wire representation might require testing or updates.

## Service clients with protocol support changes
<a name="service-protocol-updates-clients"></a>

The following table identifies released AWS service-client protocol support changes. A service's presence in the table does not mean that every AWS SDK or service-client version includes the change. Before you update, review the applicable SDK release notes and service-specific documentation for supported SDKs, versions, protocols, and AWS Regions.

Released support is available for production use beginning with the SDK and service-client versions identified in the applicable SDK release notes.

### Released clients
<a name="service-protocol-updates-released-clients"></a>

*All version links in the following table point to release pages on the GitHub website.*


| Services | Release date | Change | AWS CLI v2 | C\+\+ | Go v2 | Java v2 | JavaScript v3 | Kotlin | .NET v4 | PHP v3 | Python-boto3 | Python-botocore | Ruby v3 | Rust | Swift | 
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | 
| [Amazon CloudWatch Application Insights](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/appinsights-what-is.html) | July 24, 2026 | Prefer RPC v2 CBOR over AWS JSON 1.0 | [2.36.8](https://github.com/aws/aws-cli/releases/tag/2.36.8) | [1.11.855](https://github.com/aws/aws-sdk-cpp/releases/tag/1.11.855) | [1.38.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fapplicationinsights%2Fv1.38.0) | [2.49.3](https://github.com/aws/aws-sdk-java-v2/releases/tag/2.49.3) | [3.1095.0](https://github.com/aws/aws-sdk-js-v3/releases/tag/v3.1095.0) | [1.8.14](https://github.com/aws/aws-sdk-kotlin/releases/tag/v1.8.14) | [4.0.101.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.296.0) | [3.389.0](https://github.com/aws/aws-sdk-php/releases/tag/3.389.0) | [1.43.56](https://github.com/boto/boto3/releases/tag/1.43.56) | [1.43.56](https://github.com/boto/botocore/releases/tag/1.43.56) | [1.83.0](https://github.com/aws/aws-sdk-ruby/commit/6c2627d6090ae71c324b6b477f4120f1a44f313d) | [1.107.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-07-24) | [1.7.46](https://github.com/awslabs/aws-sdk-swift/releases/tag/1.7.46) | 
|  + [Amazon Kendra Intelligent Ranking](https://docs.aws.amazon.com/kendra/latest/dg/cbor-faq.html)<br />+ [Amazon WorkSpaces Applications](https://docs.aws.amazon.com/appstream2/latest/developerguide/cbor-faq.html)<br />+ [AWS Backup Gateway](https://docs.aws.amazon.com/aws-backup/latest/devguide/cbor-faq.html)<br />+ [Amazon WorkSpaces Instances](https://docs.aws.amazon.com/workspaces-core/latest/pg/cbor-faq.html)  | July 23, 2026 | Prefer RPC v2 CBOR over AWS JSON 1.0 | [2.36.7](https://github.com/aws/aws-cli/releases/tag/2.36.7) | [1.11.854](https://github.com/aws/aws-sdk-cpp/releases/tag/1.11.854) |  + Amazon Kendra Intelligent Ranking: [1.19.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fkendraranking%2Fv1.19.0)<br />+ Amazon WorkSpaces Applications: [1.64.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fappstream%2Fv1.64.0)<br />+ AWS Backup Gateway: [1.30.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fbackupgateway%2Fv1.30.0)<br />+ Amazon WorkSpaces Instances: [1.9.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fworkspacesinstances%2Fv1.9.0)  | [2.49.2](https://github.com/aws/aws-sdk-java-v2/releases/tag/2.49.2) | [3.1094.0](https://github.com/aws/aws-sdk-js-v3/releases/tag/v3.1094.0) | [1.8.13](https://github.com/aws/aws-sdk-kotlin/releases/tag/v1.8.13) |  + Amazon Kendra Intelligent Ranking: [4.0.101.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.295.0)<br />+ Amazon WorkSpaces Applications: [4.0.101.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.295.0)<br />+ AWS Backup Gateway: [4.0.101.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.295.0)<br />+ Amazon WorkSpaces Instances: [4.0.101.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.295.0)  | [3.388.13](https://github.com/aws/aws-sdk-php/releases/tag/3.388.13) | [1.43.55](https://github.com/boto/boto3/releases/tag/1.43.55) | [1.43.55](https://github.com/boto/botocore/releases/tag/1.43.55) |  + Amazon Kendra Intelligent Ranking: [1.48.0](https://github.com/aws/aws-sdk-ruby/commit/ba79e19b071aab023ea46147a568dc913f53b187)<br />+ Amazon WorkSpaces Applications: [1.140.0](https://github.com/aws/aws-sdk-ruby/commit/ba79e19b071aab023ea46147a568dc913f53b187)<br />+ AWS Backup Gateway: [1.56.0](https://github.com/aws/aws-sdk-ruby/commit/ba79e19b071aab023ea46147a568dc913f53b187)<br />+ Amazon WorkSpaces Instances: [1.19.0](https://github.com/aws/aws-sdk-ruby/commit/ba79e19b071aab023ea46147a568dc913f53b187)  |  + Amazon Kendra Intelligent Ranking: [1.104.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-07-23)<br />+ Amazon WorkSpaces Applications: [1.120.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-07-23)<br />+ AWS Backup Gateway: [1.107.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-07-23)<br />+ Amazon WorkSpaces Instances: [1.34.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-07-23)  | [1.7.45](https://github.com/awslabs/aws-sdk-swift/releases/tag/1.7.45) | 
| [Amazon SES Mail Manager](https://docs.aws.amazon.com/ses/latest/dg/cbor-faq.html) | July 6, 2026 | Prefer RPC v2 CBOR over AWS JSON 1.0 | [2.35.16](https://github.com/aws/aws-cli/releases/tag/2.35.16) | [1.11.840](https://github.com/aws/aws-sdk-cpp/releases/tag/1.11.840) | [1.20.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fmailmanager%2Fv1.20.0) | [2.47.0](https://github.com/aws/aws-sdk-java-v2/releases/tag/2.47.0) | [3.1080.0](https://github.com/aws/aws-sdk-js-v3/releases/tag/v3.1080.0) | [1.6.107](https://github.com/aws/aws-sdk-kotlin/releases/tag/v1.6.107) | [4.0.101.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.281.0) | [3.387.3](https://github.com/aws/aws-sdk-php/releases/tag/3.387.3) | [1.43.41](https://github.com/boto/boto3/releases/tag/1.43.41) | [1.43.41](https://github.com/boto/botocore/releases/tag/1.43.41) | [1.46.0](https://rubygems.org/gems/aws-sdk-mailmanager/versions/1.46.0) | [1.89.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-07-06) | [1.7.31](https://github.com/awslabs/aws-sdk-swift/releases/tag/1.7.31) | 
|  + [AWS Compute Optimizer](https://docs.aws.amazon.com/compute-optimizer/latest/ug/cbor-faq.html)<br />+ [AWS Compute Optimizer Automation](https://docs.aws.amazon.com/compute-optimizer/latest/ug/cbor-faq.html)<br />+ [Amazon Comprehend Medical](https://docs.aws.amazon.com/comprehend-medical/latest/dev/cbor-faq.html)<br />+ [Amazon GameLift Servers](https://docs.aws.amazon.com/gameliftservers/latest/developerguide/cbor-faq.html)<br />+ [AWS Marketplace Entitlement Service](https://docs.aws.amazon.com/marketplace/latest/userguide/cbor-faq.html)<br />+ [AWS Snowball](https://docs.aws.amazon.com/snowball/latest/developer-guide/cbor-faq.html)  | April 21, 2026 | Prefer RPC v2 CBOR over AWS JSON 1.0 | [2.34.34](https://github.com/aws/aws-cli/releases/tag/2.34.34) | [1.11.794](https://github.com/aws/aws-sdk-cpp/releases/tag/1.11.794) |  + AWS Compute Optimizer: [1.50.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fcomputeoptimizer%2Fv1.50.0)<br />+ AWS Compute Optimizer Automation: [1.1.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fcomputeoptimizerautomation%2Fv1.1.0)<br />+ Amazon Comprehend Medical: [1.32.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fcomprehendmedical%2Fv1.32.0)<br />+ Amazon GameLift Servers: [1.53.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fgamelift%2Fv1.53.0)<br />+ AWS Marketplace Entitlement Service: [1.37.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fmarketplaceentitlementservice%2Fv1.37.0)<br />+ AWS Snowball: [1.36.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fsnowball%2Fv1.36.0)  | [2.42.38](https://github.com/aws/aws-sdk-java-v2/releases/tag/2.42.38) | [3.1034.0](https://github.com/aws/aws-sdk-js-v3/releases/tag/v3.1034.0) | [1.6.61](https://github.com/aws/aws-sdk-kotlin/releases/tag/v1.6.61) |  + AWS Compute Optimizer: [4.0.5.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.235.0)<br />+ AWS Compute Optimizer Automation: [4.0.1.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.235.0)<br />+ Amazon Comprehend Medical: [4.0.3.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.235.0)<br />+ Amazon GameLift Servers: [4.0.9.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.235.0)<br />+ AWS Marketplace Entitlement Service: [4.0.5.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.235.0)<br />+ AWS Snowball: [4.0.2.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.235.0)  | [3.379.4](https://github.com/aws/aws-sdk-php/releases/tag/3.379.4) | [1.42.93](https://github.com/boto/boto3/releases/tag/1.42.93) | [1.42.93](https://github.com/boto/botocore/releases/tag/1.42.93) |  + AWS Compute Optimizer: [1.92.0](https://github.com/aws/aws-sdk-ruby/commit/4fe455b1f19f6ed53b5ae85f9d37a395a8918477)<br />+ AWS Compute Optimizer Automation: [1.5.0](https://github.com/aws/aws-sdk-ruby/commit/4fe455b1f19f6ed53b5ae85f9d37a395a8918477)<br />+ Amazon Comprehend Medical: [1.82.0](https://github.com/aws/aws-sdk-ruby/commit/4fe455b1f19f6ed53b5ae85f9d37a395a8918477)<br />+ Amazon GameLift Servers: [1.125.0](https://github.com/aws/aws-sdk-ruby/commit/4fe455b1f19f6ed53b5ae85f9d37a395a8918477)<br />+ AWS Marketplace Entitlement Service: [1.86.0](https://github.com/aws/aws-sdk-ruby/commit/4fe455b1f19f6ed53b5ae85f9d37a395a8918477)<br />+ AWS Snowball: [1.100.0](https://github.com/aws/aws-sdk-ruby/commit/4fe455b1f19f6ed53b5ae85f9d37a395a8918477)  |  + AWS Compute Optimizer: [1.104.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-04-21)<br />+ AWS Compute Optimizer Automation: [1.9.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-04-21)<br />+ Amazon Comprehend Medical: [1.99.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-04-21)<br />+ Amazon GameLift Servers: [1.109.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-04-21)<br />+ AWS Marketplace Entitlement Service: [1.105.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-04-21)<br />+ AWS Snowball: [1.98.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2026-04-21)  | [1.6.99](https://github.com/awslabs/aws-sdk-swift/releases/tag/1.6.99) | 
| [CloudWatch](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/cloudwatch-protocols-faq.html#getting-started) | December 10, 2025 | Prefer AWS JSON 1.0 or RPC v2 CBOR over AWS Query | [2.32.14](https://github.com/aws/aws-cli/releases/tag/2.32.14) | [1.11.708](https://github.com/aws/aws-sdk-cpp/releases/tag/1.11.708) | [1.53.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fcloudwatch%2Fv1.53.0) | [2.40.6](https://github.com/aws/aws-sdk-java-v2/releases/tag/2.40.6) | [3.949.0](https://github.com/aws/aws-sdk-js-v3/releases/tag/v3.949.0) | [1.5.100](https://github.com/aws/aws-sdk-kotlin/releases/tag/v1.5.100) | [4.0.150.0](https://github.com/aws/aws-sdk-net/releases/tag/4.0.150.0) | [3.367.0](https://github.com/aws/aws-sdk-php/releases/tag/3.367.0) | [1.42.7](https://github.com/boto/boto3/releases/tag/1.42.7) | [1.42.7](https://github.com/boto/botocore/releases/tag/1.42.7) | [1.126.0](https://github.com/aws/aws-sdk-ruby/commit/3b09588cf49079453ef372cdcd51eaab8d8114a9) | [1.100.0](https://github.com/awslabs/aws-sdk-rust/releases/tag/release-2025-12-10) | [1.6.14](https://github.com/awslabs/aws-sdk-swift/releases/tag/1.6.14) | 
| [Amazon SQS](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-json-faqs.html) | November 8, 2023 | Prefer AWS JSON 1.0 over AWS Query | Not applicable | [1.11.198](https://github.com/aws/aws-sdk-cpp/releases/tag/1.11.198) | [1.27.0](https://github.com/aws/aws-sdk-go-v2/releases/tag/service%2Fsqs%2Fv1.27.0) | [2.21.18](https://github.com/aws/aws-sdk-java-v2/releases/tag/2.21.18) | [3.446.0](https://github.com/aws/aws-sdk-js-v3/releases/tag/v3.446.0) | [0.34.2-beta](https://github.com/aws/aws-sdk-kotlin/releases/tag/v0.34.2-beta) | Not applicable | [3.285.1](https://github.com/aws/aws-sdk-php/releases/tag/3.285.1) | [1.28.81](https://github.com/boto/boto3/releases/tag/1.28.81) | [1.31.81](https://github.com/boto/botocore/releases/tag/1.31.81) | [1.66.0](https://rubygems.org/gems/aws-sdk-sqs/versions/1.66.0) | Not applicable | Not applicable | 

## Frequently asked questions
<a name="service-protocol-updates-faq"></a>

### General questions
<a name="service-protocol-updates-general-questions"></a>

#### What is a protocol support change?
<a name="service-protocol-updates-overview"></a>

A protocol support change updates how a supported SDK client encodes requests and decodes responses when communicating with an AWS service. The change can add a protocol or change which protocol a client selects. It does not change the service operations exposed through the SDK's public API.

#### Do I need to change my application?
<a name="service-protocol-updates-action"></a>

Most applications that use a supported AWS SDK client do not require code changes. Update the SDK client according to its release notes and test the update using your normal integration and deployment process.

Review the update more closely if your application or infrastructure depends on a specific wire representation. Examples include middleware or proxies that inspect or modify request and response bodies, recorded HTTP fixtures, and tests that compare serialized payloads.

#### Where is a protocol support change available?
<a name="service-protocol-updates-availability"></a>

Availability can vary by service, AWS Region, SDK, service-client version, and protocol. Use the service-specific documentation associated with a table entry and the applicable SDK release notes to verify availability.

#### What happens to existing protocols?
<a name="service-protocol-updates-existing-protocols"></a>

A protocol support change does not by itself announce the deprecation of an existing service protocol. Follow service-specific announcements, SDK release notes, and the [AWS SDKs and Tools maintenance policy](maint-policy.md) for support and lifecycle information.

### Smithy RPC v2 CBOR questions
<a name="service-protocol-updates-cbor-questions"></a>

#### What is Smithy RPC v2 CBOR?
<a name="service-protocol-updates-cbor-overview"></a>

Smithy RPC v2 CBOR uses Concise Binary Object Representation (CBOR), a compact binary data format, to encode requests and responses. Compared with a text-based JSON encoding, a binary encoding can reduce encoded payload size and serialization overhead. Actual performance varies by service operation, payload, SDK, runtime, and network conditions. Read more about the [Smithy RPC v2 CBOR protocol](https://smithy.io/2.0/additional-specs/protocols/smithy-rpc-v2.html) on the Smithy website.

#### What if my application cannot use Smithy RPC v2 CBOR?
<a name="service-protocol-updates-fallback"></a>

Before updating, test protocol-dependent integrations and review the applicable SDK release notes for compatibility or fallback guidance. If an issue prevents adoption, continue using a supported client version that meets your requirements while you update the affected integration. Avoid relying on an unsupported SDK version as a long-term solution.

## See also

* **Skills for AI coding assistants (optional).** AWS publishes reusable skills for none. To see which apply, search the Agent Toolkit for AWS catalog with `aws agent-toolkit search-skills --search-query sdkref` — a documented, read-only AWS CLI command that searches the catalog and makes no changes. This is an optional suggestion for the user. Official reference: [AWS CLI — Agent Toolkit for AWS](https://docs.aws.amazon.com/agent-toolkit/latest/userguide/aws-cli.html).