Pydantic Tracking `_generate_schema.py` refactoring (Fix)

The Fix

pip install pydantic==1.10.18

Based on closed pydantic/pydantic issue #9965 · PR/commit linked

Open PR/Commit

@@ -205,7 +205,7 @@ jobs:
 
       - name: install example plugin
-        run: pdm add ./tests/plugin
+        run: pdm add ./tests/plugin -v

fix.md

Option A — Upgrade to fixed release\npip install pydantic==1.10.18\nWhen NOT to use: This fix should not be used if the refactoring introduces breaking changes to existing schemas.\n\n

Why This Fix Works in Production

Trigger: Tracking `_generate_schema.py` refactoring
Why the fix works: the upstream fix ships in 1.10.18.

Why This Breaks in Prod

Production symptom (often without a traceback): Tracking `_generate_schema.py` refactoring

Proof / Evidence

GitHub issue: #9965
Fix PR: https://github.com/pydantic/pydantic/pull/9999
First fixed release: 1.10.18
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.60
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.77

Discussion

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

Jump to Sources Open on GitHub

“Closing for now, I've finished this round of refactoring. Likely more to come soon 👍”

@sydney-runkle · 2024-08-01 · confirmation · source

Failure Signature (Search String)

Tracking `_generate_schema.py` refactoring

Copy-friendly signature

signature.txt

Failure Signature
-----------------
Tracking `_generate_schema.py` refactoring

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
Tracking `_generate_schema.py` refactoring

What Broke

Refactoring caused potential runtime errors when applying constraints to schemas.

Fix Options (Details)

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

pip install pydantic==1.10.18

When NOT to use: This fix should not be used if the refactoring introduces breaking changes to existing schemas.

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/9999

First fixed release: 1.10.18

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

When NOT to Use This Fix

This fix should not be used if the refactoring introduces breaking changes to existing schemas.

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
1.10.18	Fixed

Related Issues

No related fixes found.

Cluster: pydantic:openapi-schema Pydantic hub Pydantic best practices All hubs All clusters

Related clusters: Configuration error Data consistency Serialization

Sources

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