Pydantic `PydanticUserError` raised when `model

The Fix

pip install pydantic==2.9.2

Based on closed pydantic/pydantic issue #10411 · 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

@@ -120,7 +120,7 @@ def for_model(cls, bases: tuple[type[Any], ...], namespace: dict[str, Any], kwar
 
         raw_annotations = namespace.get('__annotations__', {})
-        if raw_annotations.get('model_config') and not config_dict_from_namespace:
+        if raw_annotations.get('model_config') and config_dict_from_namespace is None:
             raise PydanticUserError(

repro.py

from pydantic import BaseModel, ConfigDict

# this works
class Model(BaseModel):
    model_config = {}

# this also works
class Model(BaseModel):
    model_config: ConfigDict = {"str_max_length": 10}

# this raises PydanticUserError
class Model(BaseModel):
    model_config: ConfigDict = {}

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==2.9.2\nWhen NOT to use: This fix should not be applied if model_config is intended to be used as a field name.\n\n

Why This Fix Works in Production

Trigger: `PydanticUserError` raised when `model_config` has type annotation and is empty
Mechanism: The logic incorrectly raises an error when model_config is empty but annotated
Why the fix works: Fixes a PydanticUserError raised when model_config has a type annotation but is empty. (first fixed release: 2.9.2).

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 logic incorrectly raises an error when model_config is empty but annotated
Surfaces as: `PydanticUserError` raised when `model_config` has type annotation and is empty

Proof / Evidence

GitHub issue: #10411
Fix PR: https://github.com/pydantic/pydantic/pull/10412
First fixed release: 2.9.2
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
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

“### Initial Checks - [X] I confirm that I'm using Pydantic V2 ### Description When model_config has a type annotation (model_config: ConfigDict) and is also empty, Pydantic raises a PydanticUserError. (I realize this case is a bit contrived”

Issue thread · issue description · source

Failure Signature (Search String)

`PydanticUserError` raised when `model_config` has type annotation and is empty

Error Message

Stack trace

error.txt

Error Message
-------------
`PydanticUserError` raised when `model_config` has type annotation and is empty

Minimal Reproduction

repro.py

from pydantic import BaseModel, ConfigDict

# this works
class Model(BaseModel):
    model_config = {}

# this also works
class Model(BaseModel):
    model_config: ConfigDict = {"str_max_length": 10}

# this raises PydanticUserError
class Model(BaseModel):
    model_config: ConfigDict = {}

Environment

Python: 3.12
Pydantic: 2

What Broke

Users encounter a PydanticUserError when using an empty model_config with type annotations.

Why It Broke

The logic incorrectly raises an error when model_config is empty but annotated

Fix Options (Details)

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

pip install pydantic==2.9.2

When NOT to use: This fix should not be applied if model_config is intended to be used as a field name.

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/10412

First fixed release: 2.9.2

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

When NOT to Use This Fix

This fix should not be applied if model_config is intended to be used as a field name.

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
2.9.2	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 `PydanticUserError` raised when `model_config` has type annotation and is empty (Fix)