Pydantic model_rebuild() doesn't respect

The Fix

pip install pydantic==2.11.3

Based on closed pydantic/pydantic issue #11696 · PR/commit linked

Production note: Most teams hit this during upgrades or environment changes. Roll out with a canary and smoke critical endpoints (health, OpenAPI/docs) before 100%.

Jump to Verify Open PR/Commit

@@ -319,6 +319,7 @@ def rebuild_model_fields(
                 rebuilt_fields[f_name] = field_info
             else:
+                existing_desc = field_info.description
                 ann = _typing_extra.eval_type(
                     field_info._original_annotation,

repro.py

from __future__ import annotations
from pydantic import BaseModel

class Model1(BaseModel, use_attribute_docstrings=True):
    b: Model2
    """doc1"""

class Model2(BaseModel, use_attribute_docstrings=True):
    pass

print(Model1.model_fields)
Model1.model_rebuild()
print(Model1.model_fields)

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==2.11.3\nWhen NOT to use: This fix should not be applied if the model does not use forward references.\n\n

Why This Fix Works in Production

Trigger: model_rebuild() doesn't respect use_attribute_docstrings
Mechanism: The rebuild_model_fields() method overwrites existing FieldInfo, losing descriptions from docstrings
Why the fix works: Preserves the field description when rebuilding model fields, addressing a regression that caused descriptions to be lost with forward references. (first fixed release: 2.11.3).

Production impact:

If left unfixed, the same config can fail only in production (env differences), causing startup failures or partial feature outages.

Why This Breaks in Prod

Shows up under Python 3.12 in real deployments (not just unit tests).
The rebuild_model_fields() method overwrites existing FieldInfo, losing descriptions from docstrings
Production symptom (often without a traceback): model_rebuild() doesn't respect use_attribute_docstrings

Proof / Evidence

GitHub issue: #11696
Fix PR: https://github.com/pydantic/pydantic/pull/11698
First fixed release: 2.11.3
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.95
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.65

Discussion

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

Jump to Sources Open on GitHub

“### Initial Checks - [x] I confirm that I'm using Pydantic V2 ### Description I'm writing a script to generate documentation for Pydantic classes. I'm using use_attribute_docstrings and have noticed that the docstring description gets lost”

Issue thread · issue description · source

Failure Signature (Search String)

model_rebuild() doesn't respect use_attribute_docstrings
Note the missing description in the second line.

Copy-friendly signature

signature.txt

Failure Signature
-----------------
model_rebuild() doesn't respect use_attribute_docstrings
Note the missing description in the second line.

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
model_rebuild() doesn't respect use_attribute_docstrings
Note the missing description in the second line.

Minimal Reproduction

repro.py

from __future__ import annotations
from pydantic import BaseModel

class Model1(BaseModel, use_attribute_docstrings=True):
    b: Model2
    """doc1"""

class Model2(BaseModel, use_attribute_docstrings=True):
    pass

print(Model1.model_fields)
Model1.model_rebuild()
print(Model1.model_fields)

Environment

Python: 3.12
Pydantic: 2

What Broke

Model documentation generation fails to include field descriptions when using forward references.

Why It Broke

The rebuild_model_fields() method overwrites existing FieldInfo, losing descriptions from docstrings

Fix Options (Details)

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

pip install pydantic==2.11.3

When NOT to use: This fix should not be applied if the model does not use forward references.

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/11698

First fixed release: 2.11.3

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

When NOT to Use This Fix

This fix should not be applied if the model does not use forward references.

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
2.11.3	Fixed

Related Issues

No related fixes found.

Cluster: pydantic:configuration-error Pydantic hub Pydantic best practices All hubs All clusters

Related clusters: Data consistency OpenAPI schema Serialization

Sources

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

Pydantic model_rebuild() doesn't respect use_attribute_docstrings (Fix)