Pydantic Schema generation loses Field annotations when

The Fix

pip install pydantic==2.11.0

Based on closed pydantic/pydantic issue #11470 · PR/commit linked

Jump to Verify Open PR/Commit

@@ -250,7 +250,6 @@ By leveraging the new [`type` statement](https://typing.readthedocs.io/en/latest
 
     from annotated_types import Gt
-    from typing_extensions import TypeAliasType
 
     from pydantic import BaseModel

repro.py

pydantic version: 2.10.6
        pydantic-core version: 2.27.2
          pydantic-core build: profile=release pgo=false
                 install path: /path/to/venv/lib/python3.13/site-packages/pydantic
               python version: 3.13.1 (main, Dec  3 2024, 17:59:52) [Clang 19.1.5 ]
                     platform: macOS-15.3.1-arm64-arm-64bit-Mach-O
             related packages: mypy-1.15.0 fastapi-0.115.8 pydantic-settings-2.7.1 typing_extensions-4.12.2
                       commit: unknown

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

fix.md

Option A — Upgrade to fixed release\npip install pydantic==2.11.0\nWhen NOT to use: This fix should not be applied if backward compatibility with previous Pydantic versions is required.\n\n

Why This Fix Works in Production

Trigger: Schema generation loses Field annotations when using PEP 695 type alias syntax
Mechanism: Pydantic fails to include Field annotations in JSON schemas when using PEP 695 type alias syntax
Why the fix works: Fixes the JSON Schema generation issue where Field annotations were lost when using PEP 695 type alias syntax. (first fixed release: 2.11.0).

Production impact:

If left unfixed, this can cause silent data inconsistencies that propagate (bad cache entries, incorrect downstream decisions).

Why This Breaks in Prod

Shows up under Python 3.13 in real deployments (not just unit tests).
Pydantic fails to include Field annotations in JSON schemas when using PEP 695 type alias syntax
Production symptom (often without a traceback): Schema generation loses Field annotations when using PEP 695 type alias syntax

Proof / Evidence

GitHub issue: #11470
Fix PR: https://github.com/pydantic/pydantic/pull/11475
First fixed release: 2.11.0
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.95
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.59

Discussion

High-signal excerpts from the issue thread (symptoms, repros, edge-cases).

Jump to Sources Open on GitHub

“This just so happens to have been discussed not long ago here.”

@Viicos · 2025-02-20 · source

Failure Signature (Search String)

Schema generation loses Field annotations when using PEP 695 type alias syntax
When declaring a type with a PEP 695 type alias, Pydantic does not include details provided via a `Field` annotation (like `examples`, `description`, `alias`, etc.) in generated

Copy-friendly signature

signature.txt

Failure Signature
-----------------
Schema generation loses Field annotations when using PEP 695 type alias syntax
When declaring a type with a PEP 695 type alias, Pydantic does not include details provided via a `Field` annotation (like `examples`, `description`, `alias`, etc.) in generated JSON schemas.

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
Schema generation loses Field annotations when using PEP 695 type alias syntax
When declaring a type with a PEP 695 type alias, Pydantic does not include details provided via a `Field` annotation (like `examples`, `description`, `alias`, etc.) in generated JSON schemas.

Minimal Reproduction

repro.py

pydantic version: 2.10.6
        pydantic-core version: 2.27.2
          pydantic-core build: profile=release pgo=false
                 install path: /path/to/venv/lib/python3.13/site-packages/pydantic
               python version: 3.13.1 (main, Dec  3 2024, 17:59:52) [Clang 19.1.5 ]
                     platform: macOS-15.3.1-arm64-arm-64bit-Mach-O
             related packages: mypy-1.15.0 fastapi-0.115.8 pydantic-settings-2.7.1 typing_extensions-4.12.2
                       commit: unknown

Environment

Python: 3.13
Pydantic: 2

What Broke

Generated JSON schemas lack expected metadata, leading to incomplete API documentation.

Why It Broke

Pydantic fails to include Field annotations in JSON schemas when using PEP 695 type alias syntax

Fix Options (Details)

Option A — Upgrade to fixed release Safe default (recommended)

pip install pydantic==2.11.0

When NOT to use: This fix should not be applied if backward compatibility with previous Pydantic versions is required.

Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.

Fix reference: https://github.com/pydantic/pydantic/pull/11475

First fixed release: 2.11.0

Last verified: 2026-02-09. Validate in your environment.

When NOT to Use This Fix

This fix should not be applied if backward compatibility with previous Pydantic versions is required.

Verify Fix

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

Did This Fix Work in Your Case?

Quick signal helps us prioritize which fixes to verify and improve.

Prevention

Add a CI check that diffs key outputs after upgrades (OpenAPI schema snapshots, JSON payload shapes, CLI output).
Upgrade behind a canary and run integration tests against the canary before 100% rollout.

Version Compatibility Table

Version	Status
2.11.0	Fixed

Related Issues

No related fixes found.

Cluster: pydantic:data-consistency Pydantic hub Pydantic best practices All hubs All clusters

Related clusters: Configuration error OpenAPI schema Serialization

Sources

We don’t republish the full GitHub discussion text. Use the links above for context.

Pydantic Schema generation loses Field annotations when using PEP 695 type alias syntax (Fix)