●Change8

Migrating to Anthropic SDK v0.77.0

Version v0.77.0 introduces 2 breaking changes. This guide details how to update your code.

Released: 1/29/2026

2
Breaking Changes
1
Migration Steps
3
Affected Symbols

⚠️ Check Your Code

If you use any of these symbols, you need to read this guide:

Messages API (Structured Outputs)output_configoutput_format

Breaking Changes

●Issue #1

The mechanism for sending structured output configuration has changed: it now uses `output_config` instead of the deprecated `output_format` when sending message requests. Users relying on the old parameter name must update their calls.

●Issue #2

A class that caused a breaking change was removed (see issue #1333).

Migration Steps

  1. 1
    If you were configuring structured outputs, migrate from using `output_format` to using `output_config` in your message sending calls.

Release Summary

This release introduces support for Structured Outputs in the Messages API, migrating the configuration mechanism to use `output_config`. It also includes several bug fixes related to structured output headers and general client improvements.

Need More Details?

View the full release notes and all changes for Anthropic SDK v0.77.0.

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