API version header
An API version header tells the provider which request contract to apply. On the Claude API the header is anthropic-version, and changing it can reject fields on a model that is still available.
Last reviewed . Publisher: SunsetDiff. A source line names the day that page was read.
The rows below are copied from this site's model records. A shutdown cell is the date stored for that provider, not a date copied from another host.
Anthropic
If you call the Claude API without an SDK, you set the anthropic-version header. The versioning page still lists 2023-06-01 and does not call that version deprecated. API version 2026-10-21 returns HTTP 400 for temperature, top_p, and top_k on every model, even at the default value.
The versioning page says 2026-10-21 is available on the Claude API, Claude Platform on AWS, Microsoft Foundry, and Google Cloud. On Amazon Bedrock it is available for Claude 4.7 and later models. For other models on Bedrock, the page points to the migration guide.
The first SDK and CLI versions that send 2026-10-21 are named on the migration guide and on the SunsetDiff error page linked below.
Sources: Claude API versioning , Claude API migration 2026-10-21 , checked October 22, 2026.
OpenAI, Gemini, Vertex, Bedrock, and Azure
The OpenAI, Gemini, Vertex, and Bedrock retirement pages read for this glossary do not define an anthropic-version header. Bedrock's exception is the Claude availability sentence above.
Azure model retirement is a deployment and a model version, which is a dated model such as gpt-4o 2024-05-13. That version is not the anthropic-version header.
Sources: OpenAI deprecations , Gemini API deprecations , Vertex model versions , Bedrock model lifecycle , Foundry Models lifecycle , checked October 22, 2026.
Rows from this dataset
This term is a request header, not a model status. The error page names the models and the API version.