Anthropic marks Claude 4 Sonnet and Opus as deprecated in Python SDK v0.95.0

Anthropic released version 0.95.0 of its Python SDK on April 14, 2026, with the primary change being the deprecation of Claude 4 Sonnet and Opus models.

Deprecation details

The SDK now marks both Claude 4 Sonnet and Claude 4 Opus as deprecated, according to the release notes. This typically signals that these models will be phased out in favor of newer versions, though Anthropic has not specified an end-of-life date or recommended migration path in the changelog.

Developers using these models in production should expect migration requirements in future releases. Anthropic has not announced replacement models or provided guidance on which Claude variants should be used instead.

Additional changes

The release also includes an authentication update for Bedrock deployments. The SDK now uses an auth header for the Mantle client when running Claude models through AWS Bedrock, improving compatibility with Amazon's infrastructure.

What this means

The deprecation of Claude 4 Sonnet and Opus without immediate replacement details suggests Anthropic may be preparing to release newer model versions or consolidating its model lineup. Developers should monitor Anthropic's documentation for migration timelines and recommended alternatives.

For teams running Claude through AWS Bedrock, the authentication header change should be transparent but may require testing to ensure compatibility with existing deployment configurations. The full changelog is available on GitHub.