Pydantic some of the type annotations in `_typing

The Fix

pip install pydantic==1.10.19

Based on closed pydantic/pydantic issue #10577 · 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%.

Open PR/Commit

@@ -51,7 +51,7 @@ from datetime import datetime
 
 from pydantic import BaseModel
-from pydantic.experimental.pipeline import validate_as, validate_as_deferred
+from pydantic.experimental.pipeline import validate_as

fix.md

Option A — Upgrade to fixed release\npip install pydantic==1.10.19\nWhen NOT to use: Do not apply this fix if the type annotations are already correctly defined.\n\n

Why This Fix Works in Production

Trigger: Incorrect type annotations led to potential type evaluation issues in production.
Mechanism: Refactor namespace logic for annotations evaluation, correcting type annotations in `_typing_extra`.
Why the fix works: Refactor namespace logic for annotations evaluation, correcting type annotations in `_typing_extra`. (first fixed release: 1.10.19).

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

Production symptom (often without a traceback): Incorrect type annotations led to potential type evaluation issues in production.

Proof / Evidence

GitHub issue: #10577
Fix PR: https://github.com/pydantic/pydantic/pull/10530
First fixed release: 1.10.19
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.95
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.73

Discussion

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

Jump to Sources Open on GitHub

“@Viicos is fixing these in https://github.com/pydantic/pydantic/pull/10530, which should merge in the next few days. Thanks for pointing this out!”

@sydney-runkle · 2024-10-08 · source

Failure Signature (Search String)

Incorrect type annotations led to potential type evaluation issues in production.

Copy-friendly signature

signature.txt

Failure Signature
-----------------
Incorrect type annotations led to potential type evaluation issues in production.

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
Incorrect type annotations led to potential type evaluation issues in production.

Environment

Pydantic: 2

What Broke

Incorrect type annotations led to potential type evaluation issues in production.

Fix Options (Details)

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

pip install pydantic==1.10.19

When NOT to use: Do not apply this fix if the type annotations are already correctly defined.

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/10530

First fixed release: 1.10.19

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

When NOT to Use This Fix

Do not apply this fix if the type annotations are already correctly defined.

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
1.10.19	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 some of the type annotations in `_typing_extra` are wrong (Fix)