Pydantic Disallow Pydantic models when using `with

The Fix

pip install pydantic==2.7.2

Based on closed pydantic/pydantic issue #9397 · 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

@@ -1117,6 +1117,25 @@ except PydanticUserError as exc_info:
 ```
 
+
+## [`with_config`][pydantic.config.with_config] is used on a `BaseModel` subclass {#with-config-on-model}
+

fix.md

Option A — Upgrade to fixed release\npip install pydantic==2.7.2\nWhen NOT to use: This fix is not applicable if `with_config` is intended for non-Pydantic models.\n\n

Why This Fix Works in Production

Trigger: From https://github.com/pydantic/pydantic/issues/9389#issuecomment-2095723828, I think using `with_config` with a Pydantic model should be disallowed and…
Mechanism: Using `with_config` on a Pydantic model leads to runtime errors
Why the fix works: Disallow usage of `with_config` on a Pydantic model, resulting in a runtime error. (first fixed release: 2.7.2).

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

Using `with_config` on a Pydantic model leads to runtime errors
Production symptom (often without a traceback): From https://github.com/pydantic/pydantic/issues/9389#issuecomment-2095723828, I think using `with_config` with a Pydantic model should be disallowed and result in a runtime error.

Proof / Evidence

GitHub issue: #9397
Fix PR: https://github.com/pydantic/pydantic/pull/9398
First fixed release: 2.7.2
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.95
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.70

Discussion

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

Jump to Sources Open on GitHub

“### Initial Checks - [X] I have searched Google & GitHub for similar requests and couldn't find anything - [X] I have read and followed the docs and still think this feature is missing ### Description From https://github.com/pydantic/pydant”

Issue thread · issue description · source

Failure Signature (Search String)

From https://github.com/pydantic/pydantic/issues/9389#issuecomment-2095723828, I think using `with_config` with a Pydantic model should be disallowed and result in a runtime error.
- [ ] [Compatibility between releases](https://docs.pydantic.dev/changelog/)

Copy-friendly signature

signature.txt

Failure Signature
-----------------
From https://github.com/pydantic/pydantic/issues/9389#issuecomment-2095723828, I think using `with_config` with a Pydantic model should be disallowed and result in a runtime error.
- [ ] [Compatibility between releases](https://docs.pydantic.dev/changelog/)

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
From https://github.com/pydantic/pydantic/issues/9389#issuecomment-2095723828, I think using `with_config` with a Pydantic model should be disallowed and result in a runtime error.
- [ ] [Compatibility between releases](https://docs.pydantic.dev/changelog/)

What Broke

Runtime errors occur when `with_config` is incorrectly applied to Pydantic models.

Why It Broke

Using `with_config` on a Pydantic model leads to runtime errors

Fix Options (Details)

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

pip install pydantic==2.7.2

When NOT to use: This fix is not applicable if `with_config` is intended for non-Pydantic models.

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/9398

First fixed release: 2.7.2

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

When NOT to Use This Fix

This fix is not applicable if `with_config` is intended for non-Pydantic models.

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
2.7.2	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 Disallow Pydantic models when using `with_config` (Fix)