●Change8

Migrating to FastAPI 0.128.0

Version 0.128.0 introduces 1 breaking change. This guide details how to update your code.

Released: 12/27/2025

1
Breaking Changes
2
Migration Steps
1
Affected Symbols

⚠️ Check Your Code

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

pydantic.v1

Breaking Changes

●Issue #1

Support for pydantic.v1 has been dropped. Applications must migrate to Pydantic v2 to continue using the latest version of the library.

Migration Steps

  1. 1
    Upgrade codebase to use Pydantic v2.
  2. 2
    Replace any imports or logic relying on the pydantic.v1 compatibility layer.

Release Summary

This release officially drops support for Pydantic v1, requiring all users to migrate to Pydantic v2. Internal performance tests have also been updated to reflect this change.

Need More Details?

View the full release notes and all changes for FastAPI 0.128.0.

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