Pydantic Support for `annotated

The Fix

pip install pydantic==2.9.0

Based on closed pydantic/pydantic issue #10111 · PR/commit linked

Jump to Verify Open PR/Commit

@@ -299,17 +299,25 @@ def _apply_constraint_with_incompatibility_info(
             )
             continue
-        elif isinstance(annotation, at.Predicate):
-            predicate_name = f'{annotation.func.__qualname__} ' if hasattr(annotation.func, '__qualname__') else ''
+        elif isinstance(annotation, (at.Predicate, at.Not)):

repro.py

from functools import partial
from typing_extensions import Annotated
import annotated_types

from pydantic import AfterValidator, TypeAdapter, WithJsonSchema


def validate_not_multiple_of(x: int, y: int) -> int:
    if x % y == 0:
        raise ValueError(f"value must not be multiple of {y}")
    return x


PositiveOddInt = Annotated[
    int,
    annotated_types.Gt(0),
    AfterValidator(partial(validate_not_multiple_of, y=2)),
    WithJsonSchema({"type": "positive_odd_int"}),
]

ta = TypeAdapter(PositiveOddInt)

assert ta.validate_python(3) == 3
assert ta.dump_json(3) == b"3"
assert ta.json_schema() == {"type": "positive_odd_int"}

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==2.9.0\nWhen NOT to use: Do not use this fix if you require backward compatibility with Pydantic 1.\n\n

Why This Fix Works in Production

Trigger: json-schema for `NotMultipleOf(2)` would look like `"not": {"multipleOf": 2}`
Mechanism: Adds support for annotated_types.Not, allowing for more flexible type definitions in Pydantic.
Why the fix works: Adds support for annotated_types.Not, allowing for more flexible type definitions in Pydantic. (first fixed release: 2.9.0).

Why This Breaks in Prod

Production symptom (often without a traceback): json-schema for `NotMultipleOf(2)` would look like `"not": {"multipleOf": 2}`

Proof / Evidence

GitHub issue: #10111
Fix PR: https://github.com/pydantic/pydantic/pull/10210
First fixed release: 2.9.0
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.44

Discussion

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

Jump to Sources Open on GitHub

“@aditkumar72, good question”

@sydney-runkle · 2024-08-20 · source

“We'd welcome support for this. PRs welcome!”

@sydney-runkle · 2024-08-12 · source

“Hi @sydney-runkle, Could you please assign this to me ?”

@aditkumar72 · 2024-08-16 · source

“Hi @georgievgeorgi @sydney-runkle Can we use something like this ? If I am not mistaken, supporting annotated_types.Not would require changes in pydantic-core”

@aditkumar72 · 2024-08-17 · source

Failure Signature (Search String)

json-schema for `NotMultipleOf(2)` would look like `"not": {"multipleOf": 2}`
- [ ] [Compatibility between releases](https://docs.pydantic.dev/changelog/)

Copy-friendly signature

signature.txt

Failure Signature
-----------------
json-schema for `NotMultipleOf(2)` would look like `"not": {"multipleOf": 2}`
- [ ] [Compatibility between releases](https://docs.pydantic.dev/changelog/)

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
json-schema for `NotMultipleOf(2)` would look like `"not": {"multipleOf": 2}`
- [ ] [Compatibility between releases](https://docs.pydantic.dev/changelog/)

Minimal Reproduction

repro.py

from functools import partial
from typing_extensions import Annotated
import annotated_types

from pydantic import AfterValidator, TypeAdapter, WithJsonSchema


def validate_not_multiple_of(x: int, y: int) -> int:
    if x % y == 0:
        raise ValueError(f"value must not be multiple of {y}")
    return x


PositiveOddInt = Annotated[
    int,
    annotated_types.Gt(0),
    AfterValidator(partial(validate_not_multiple_of, y=2)),
    WithJsonSchema({"type": "positive_odd_int"}),
]

ta = TypeAdapter(PositiveOddInt)

assert ta.validate_python(3) == 3
assert ta.dump_json(3) == b"3"
assert ta.json_schema() == {"type": "positive_odd_int"}

Environment

Pydantic: 1

What Broke

Users could not define types like PositiveOddInt, leading to validation issues.

Fix Options (Details)

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

pip install pydantic==2.9.0

When NOT to use: Do not use this fix if you require backward compatibility with Pydantic 1.

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/10210

First fixed release: 2.9.0

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

When NOT to Use This Fix

Do not use this fix if you require backward compatibility with Pydantic 1.

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
2.9.0	Fixed

Related Issues

No related fixes found.

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Related clusters: Configuration error Data consistency Serialization

Sources

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

Pydantic Support for `annotated_types.Not` (Fix)