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Details

The Fix

pip install pydantic==1.10.19

Based on closed pydantic/pydantic issue #10591 · 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
@@ -1,81 +1,45 @@ @@ -1,81 +1,45 @@ -Postponed annotations (as described in [PEP563](https://www.python.org/dev/peps/pep-0563/)) "just work". +Forward annotations (wrapped in quotes) or using the `from __future__ import annotations` [future statement] +(as introduced in [PEP563](https://www.python.org/dev/peps/pep-0563/)) are supported:
fix.md
Option A — Upgrade to fixed release\npip install pydantic==1.10.19\nWhen NOT to use: This fix is not applicable if the documentation is already clear and accurate.\n\n

Why This Fix Works in Production

  • Trigger: [Docs] Page on postponed annotations is confusing (example doesn't actually contain postponed annotations?)
  • Mechanism: The documentation incorrectly presented examples that do not require postponed annotations
  • Why the fix works: Updated documentation to clarify the use of forward annotations instead of postponed annotations. (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

  • The documentation incorrectly presented examples that do not require postponed annotations
  • Production symptom (often without a traceback): [Docs] Page on postponed annotations is confusing (example doesn't actually contain postponed annotations?)

Proof / Evidence

Discussion

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

“The example is pretty contrived as it indeed does not require stringified annotations to work”
@Viicos · 2024-10-10 · source

Failure Signature (Search String)

  • [Docs] Page on postponed annotations is confusing (example doesn't actually contain postponed annotations?)
Copy-friendly signature
signature.txt
Failure Signature ----------------- [Docs] Page on postponed annotations is confusing (example doesn't actually contain postponed annotations?)

Error Message

Signature-only (no traceback captured)
error.txt
Error Message ------------- [Docs] Page on postponed annotations is confusing (example doesn't actually contain postponed annotations?)

Environment

  • Pydantic: 2

What Broke

Users may be confused by misleading documentation, leading to incorrect usage of annotations.

Why It Broke

The documentation incorrectly presented examples that do not require postponed annotations

Fix Options (Details)

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

pip install pydantic==1.10.19

When NOT to use: This fix is not applicable if the documentation is already clear and accurate.

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/10592

First fixed release: 1.10.19

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

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When NOT to Use This Fix

  • This fix is not applicable if the documentation is already clear and accurate.

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

VersionStatus
1.10.19 Fixed

Related Issues

No related fixes found.

Sources

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