Pydantic Deprecated fields bugs with forward annotations

The Fix

pip install pydantic==2.11.0

Based on closed pydantic/pydantic issue #11390 · PR/commit linked

Jump to Verify Open PR/Commit

@@ -17,7 +17,7 @@
 from pydantic.errors import PydanticUserError
 
-from . import _typing_extra
+from . import _generics, _typing_extra
 from ._config import ConfigWrapper

repro.py

from pydantic import BaseModel

from typing import Annotated
from typing_extensions import deprecated

class Model(BaseModel):
    a: Annotated[int, deprecated('test')] = 1
    b: "Annotated[Test, deprecated('test')]" = 2

Test = int

Model.model_rebuild()
Model.model_fields['b'].deprecated == 'test'
# False, should be True

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 used if the model relies on incomplete field evaluations.\n\n

Why This Fix Works in Production

Trigger: Model fields did not reflect deprecation warnings, leading to unexpected behavior in production.
Mechanism: The model fields were inaccurate due to issues with evaluating forward annotations during model rebuilding
Why the fix works: Fixes bugs related to deprecated fields with forward annotations in Pydantic models, ensuring accurate field collection during model rebuilding. (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

The model fields were inaccurate due to issues with evaluating forward annotations during model rebuilding
Production symptom (often without a traceback): Model fields did not reflect deprecation warnings, leading to unexpected behavior in production.

Proof / Evidence

GitHub issue: #11390
Fix PR: https://github.com/pydantic/pydantic/pull/11388
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: 0.68

Discussion

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

Jump to Sources Open on GitHub

“First bug: By fixing the first bug, second bug:”

Issue thread · issue description · source

Failure Signature (Search String)

Model fields did not reflect deprecation warnings, leading to unexpected behavior in production.

Copy-friendly signature

signature.txt

Failure Signature
-----------------
Model fields did not reflect deprecation warnings, leading to unexpected behavior in production.

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
Model fields did not reflect deprecation warnings, leading to unexpected behavior in production.

Minimal Reproduction

repro.py

from pydantic import BaseModel

from typing import Annotated
from typing_extensions import deprecated

class Model(BaseModel):
    a: Annotated[int, deprecated('test')] = 1
    b: "Annotated[Test, deprecated('test')]" = 2

Test = int

Model.model_rebuild()
Model.model_fields['b'].deprecated == 'test'
# False, should be True

What Broke

Model fields did not reflect deprecation warnings, leading to unexpected behavior in production.

Why It Broke

The model fields were inaccurate due to issues with evaluating forward annotations during model rebuilding

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 used if the model relies on incomplete field evaluations.

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/11388

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 used if the model relies on incomplete field evaluations.

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 Deprecated fields bugs with forward annotations (Fix)