Pydantic Annotated `NotRequired` field in `TypedDict`

The Fix

pip install pydantic==2.11.0

Based on closed pydantic/pydantic issue #11510 · 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

@@ -297,7 +297,8 @@ jobs:
 
       - name: Run ODMantic tests
-        run: pytest tests
+        # Disabled tests, as per https://github.com/art049/odmantic/issues/512:
+        run: pytest tests -k 'not test_custom_bson_serializable and not test_sync_custom_bson_serializable and not test_with_bson_serializer_override_builtin_bson'

repro.py

import typing as _t

from pydantic import BaseModel, Field

class MyTypedDict(_t.TypedDict):
    x: _t.Annotated[_t.NotRequired[str], Field(pattern="test[xyz]")]  # Does not work
    y: _t.NotRequired[str]  # This works
    z: _t.Annotated[str, Field(default="hello")]  # This works

class ComponentSpec(BaseModel):
    name: str
    args: MyTypedDict

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 `arbitrary_types_allowed` is not set to True.\n\n

Why This Fix Works in Production

Trigger: pydantic.errors.PydanticSchemaGenerationError: Unable to generate pydantic-core schema for typing.NotRequired[str]. Set `arbitrary_types_allowed=True` in the…
Mechanism: Using `Annotated` with `NotRequired` types in `TypedDict` caused schema generation errors
Why the fix works: Fixes an issue where using `Annotated` with `NotRequired` types in `TypedDict` objects caused schema generation errors. (first fixed release: 2.11.0).

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).
Using `Annotated` with `NotRequired` types in `TypedDict` caused schema generation errors
Surfaces as: pydantic.errors.PydanticSchemaGenerationError: Unable to generate pydantic-core schema for typing.NotRequired[str]. Set `arbitrary_types_allowed=True` in the model_config to…

Proof / Evidence

GitHub issue: #11510
Fix PR: https://github.com/pydantic/pydantic/pull/11479
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: 0.61

Discussion

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

Jump to Sources Open on GitHub

“This just so happens to be fixed by https://github.com/pydantic/pydantic/pull/11479, which was merged a couple days ago. The fix will be included in 2.11.”

@Viicos · 2025-03-02 · confirmation · source

Failure Signature (Search String)

pydantic.errors.PydanticSchemaGenerationError: Unable to generate pydantic-core schema for typing.NotRequired[str]. Set `arbitrary_types_allowed=True` in the model_config to

Error Message

Stack trace

error.txt

Error Message
-------------
pydantic.errors.PydanticSchemaGenerationError: Unable to generate pydantic-core schema for typing.NotRequired[str]. Set `arbitrary_types_allowed=True` in the model_config to ignore this error or implement `__get_pydantic_core_schema__` on your type to fully support it.

Minimal Reproduction

repro.py

import typing as _t

from pydantic import BaseModel, Field

class MyTypedDict(_t.TypedDict):
    x: _t.Annotated[_t.NotRequired[str], Field(pattern="test[xyz]")]  # Does not work
    y: _t.NotRequired[str]  # This works
    z: _t.Annotated[str, Field(default="hello")]  # This works

class ComponentSpec(BaseModel):
    name: str
    args: MyTypedDict

Environment

Python: 3.12
Pydantic: 2

What Broke

Schema generation errors occurred when using `Annotated` with `NotRequired` in production.

Why It Broke

Using `Annotated` with `NotRequired` types in `TypedDict` caused schema generation errors

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 `arbitrary_types_allowed` is not set to True.

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/11479

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 `arbitrary_types_allowed` is not set to True.

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: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 Annotated `NotRequired` field in `TypedDict` requires `arbitrary_types_allowed=True` (Fix)