Pydantic JSON Schema serialization of FloatEnums

The Fix

pip install pydantic==1.10.18

Based on closed pydantic/pydantic issue #10163 · 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

@@ -748,7 +748,7 @@ def literal_schema(self, schema: core_schema.LiteralSchema) -> JsonSchemaValue:
             result['type'] = 'integer'
         elif types == {float}:
-            result['type'] = 'numeric'
+            result['type'] = 'number'
         elif types == {bool}:

repro.py

from enum import Enum
import pprint
from pydantic import BaseModel


class FloatEnum(float, Enum):
    A = 0.1
    B = 0.2


class Param(BaseModel):
    score_threshold: FloatEnum


pprint.pprint(Param.model_json_schema())

# Outputs:
# {'$defs': {'FloatEnum': {'enum': [0.1, 0.2],
#                          'title': 'FloatEnum',
#                          'type': 'numeric'}},
#  'properties': {'score_threshold': {'$ref': '#/$defs/FloatEnum'}},
#  'required': ['score_threshold'],
#  'title': 'Param',
#  'type': 'object'}

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==1.10.18\nWhen NOT to use: Do not apply this fix if the JSON Schema type 'numeric' is required by your application.\n\n

Why This Fix Works in Production

Trigger: JSON Schema serialization of FloatEnums incorrectly assigns type 'numeric'
Mechanism: The enum_schema() method incorrectly assigns type 'numeric' instead of 'number' for FloatEnums
Why the fix works: Fixes the JSON Schema type assignment for FloatEnums from 'numeric' to 'number'. (first fixed release: 1.10.18).

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).
The enum_schema() method incorrectly assigns type 'numeric' instead of 'number' for FloatEnums
Production symptom (often without a traceback): JSON Schema serialization of FloatEnums incorrectly assigns type 'numeric'

Proof / Evidence

GitHub issue: #10163
Fix PR: https://github.com/pydantic/pydantic/pull/10172
First fixed release: 1.10.18
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.95
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.52

Discussion

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

Jump to Sources Open on GitHub

“Thanks for the clear example. This will be fixed in https://github.com/pydantic/pydantic/pull/10172.”

@Viicos · 2024-08-19 · confirmation · source

Failure Signature (Search String)

JSON Schema serialization of FloatEnums incorrectly assigns type 'numeric'
This causes issue with downstream tasks, where correct Json Schemas are expected. If I have misunderstood / misplaced the cause, I'm sorry! :sweat_smile:

Copy-friendly signature

signature.txt

Failure Signature
-----------------
JSON Schema serialization of FloatEnums incorrectly assigns type 'numeric'
This causes issue with downstream tasks, where correct Json Schemas are expected. If I have misunderstood / misplaced the cause, I'm sorry! :sweat_smile:

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
JSON Schema serialization of FloatEnums incorrectly assigns type 'numeric'
This causes issue with downstream tasks, where correct Json Schemas are expected. If I have misunderstood / misplaced the cause, I'm sorry! :sweat_smile:

Minimal Reproduction

repro.py

from enum import Enum
import pprint
from pydantic import BaseModel


class FloatEnum(float, Enum):
    A = 0.1
    B = 0.2


class Param(BaseModel):
    score_threshold: FloatEnum


pprint.pprint(Param.model_json_schema())

# Outputs:
# {'$defs': {'FloatEnum': {'enum': [0.1, 0.2],
#                          'title': 'FloatEnum',
#                          'type': 'numeric'}},
#  'properties': {'score_threshold': {'$ref': '#/$defs/FloatEnum'}},
#  'required': ['score_threshold'],
#  'title': 'Param',
#  'type': 'object'}

Environment

Python: 3.11
Pydantic: 2

What Broke

Incorrect JSON Schema type assignment leads to downstream validation failures.

Why It Broke

The enum_schema() method incorrectly assigns type 'numeric' instead of 'number' for FloatEnums

Fix Options (Details)

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

pip install pydantic==1.10.18

When NOT to use: Do not apply this fix if the JSON Schema type 'numeric' is required by your application.

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/10172

First fixed release: 1.10.18

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

When NOT to Use This Fix

Do not apply this fix if the JSON Schema type 'numeric' is required by your application.

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
1.10.18	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 JSON Schema serialization of FloatEnums incorrectly assigns type 'numeric' (Fix)