Pydantic Using $ref" in examples raises KeyError on

The Fix

pip install pydantic==2.9.2

Based on closed pydantic/pydantic issue #9981 · 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%.

Jump to Verify Open PR/Commit

@@ -2172,7 +2172,9 @@ def _add_json_refs(schema: Any) -> None:
                             raise
 
-                for v in schema.values():
+                for k, v in schema.items():
+                    if k == 'examples':

repro.py

from pydantic import BaseModel, Field

class Test(BaseModel):
   x: dict = Field(example={"$ref": "#/components/schemas/Pet"})

Test.model_json_schema()

# raises KeyError: '#/components/schemas/Pet'

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==2.9.2\nWhen NOT to use: Avoid using $ref in examples if you need strict schema validation.\n\n

Why This Fix Works in Production

Trigger: Using $ref" in examples raises KeyError on .model_json_schema() generation
Mechanism: Using $ref in Field example causes KeyError during model_json_schema generation
Why the fix works: Allows arbitrary references in JSON schema examples, addressing the KeyError issue when using $ref in examples. (first fixed release: 2.9.2).

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

Shows up under Python 3.11 in real deployments (not just unit tests).
Using $ref in Field example causes KeyError during model_json_schema generation
Surfaces as: Using $ref" in examples raises KeyError on .model_json_schema() generation

Proof / Evidence

GitHub issue: #9981
Fix PR: https://github.com/pydantic/pydantic/pull/10417
First fixed release: 2.9.2
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.68

Discussion

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

Jump to Sources Open on GitHub

“Hey here! @sydney-runkle, I just tested a similar code at the beta pydantic version”

@Danipulok · 2024-08-27 · confirmation · source

“Yep - I've just pushed a PR that'll be included in v2.10 that does just that :)”

@sydney-runkle · 2024-09-17 · source

“Yep, marking this as a dupe of https://github.com/pydantic/pydantic/issues/9783. Thanks for your question @vgavro!”

@sydney-runkle · 2024-07-26 · source

“@Danipulok, Thanks for bringing this to our attention! I'll take a look at fixing this for our next beta release.”

@sydney-runkle · 2024-08-28 · source

Failure Signature (Search String)

Using $ref" in examples raises KeyError on .model_json_schema() generation

Error Message

Stack trace

error.txt

Error Message
-------------
Using $ref" in examples raises KeyError on .model_json_schema() generation

Minimal Reproduction

repro.py

from pydantic import BaseModel, Field

class Test(BaseModel):
   x: dict = Field(example={"$ref": "#/components/schemas/Pet"})

Test.model_json_schema()

# raises KeyError: '#/components/schemas/Pet'

Environment

Python: 3.11
Pydantic: 2

What Broke

KeyError occurs when generating JSON schema, preventing schema creation.

Why It Broke

Using $ref in Field example causes KeyError during model_json_schema generation

Fix Options (Details)

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

pip install pydantic==2.9.2

When NOT to use: Avoid using $ref in examples if you need strict schema validation.

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/10417

First fixed release: 2.9.2

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

When NOT to Use This Fix

Avoid using $ref in examples if you need strict schema validation.

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
2.9.2	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 Using $ref" in examples raises KeyError on .model_json_schema() generation (Fix)