Pydantic model_dump() does not include Python object for IP

The Fix

pip install pydantic==1.10.19

Based on closed pydantic/pydantic issue #10589 · 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

@@ -486,9 +486,9 @@ def get_json_schema_no_cases(_, handler: GetJsonSchemaHandler) -> JsonSchemaValu
 
     def _ip_schema(self, tp: Any) -> CoreSchema:
-        from ._validators import IP_VALIDATOR_LOOKUP
+        from ._validators import IP_VALIDATOR_LOOKUP, IpType

repro.py

import ipaddress
from pydantic import BaseModel

class Address(BaseModel):
    ip: ipaddress.IPv4Address

a = Address(ip="127.0.0.1")
print(a.model_dump())

# 2.8.2: {'ip': IPv4Address('127.0.0.1')}
# 2.9.2: {'ip': '127.0.0.1'}

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==1.10.19\nWhen NOT to use: Do not use this fix if you require string representation for IP addresses.\n\n

Why This Fix Works in Production

Trigger: model_dump() does not include Python object for IP addresses
Mechanism: The model_dump() method changed to serialize IP addresses as strings instead of Python objects
Why the fix works: Fix serialization for IP types with `mode='python'` to include the Python object instead of the string representation. (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 model_dump() method changed to serialize IP addresses as strings instead of Python objects
Production symptom (often without a traceback): model_dump() does not include Python object for IP addresses

Proof / Evidence

GitHub issue: #10589
Fix PR: https://github.com/pydantic/pydantic/pull/10594
First fixed release: 1.10.19
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.75
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.62

Discussion

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

Jump to Sources Open on GitHub

“There is no rush for me, so whatever works best for you. I'll just stick with v2.8.2 until the fix is released.”

@jderuiter · 2024-10-10 · confirmation · source

“Hi @jderuiter, Thanks for your question. Looks like this changed in https://github.com/pydantic/pydantic/pull/10112. Looking into a fix now.”

@sydney-runkle · 2024-10-10 · source

“> Hi @jderuiter, > > Thanks for your question. Looks like this changed in #10112. Looking into a fix now. Thanks a lot!”

@jderuiter · 2024-10-10 · source

“We can probably do a patch release with this fix (v2.9.3), or if you're in no rush, we could wait until v2.10, which we'll do…”

@sydney-runkle · 2024-10-10 · source

Failure Signature (Search String)

model_dump() does not include Python object for IP addresses
Since version 2.9.0, model_dump() does not seem to include a Python object for IP addresses anymore but instead includes the string representation.

Copy-friendly signature

signature.txt

Failure Signature
-----------------
model_dump() does not include Python object for IP addresses
Since version 2.9.0, model_dump() does not seem to include a Python object for IP addresses anymore but instead includes the string representation.

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
model_dump() does not include Python object for IP addresses
Since version 2.9.0, model_dump() does not seem to include a Python object for IP addresses anymore but instead includes the string representation.

Minimal Reproduction

repro.py

import ipaddress
from pydantic import BaseModel

class Address(BaseModel):
    ip: ipaddress.IPv4Address

a = Address(ip="127.0.0.1")
print(a.model_dump())

# 2.8.2: {'ip': IPv4Address('127.0.0.1')}
# 2.9.2: {'ip': '127.0.0.1'}

Environment

Pydantic: 2

What Broke

Users receive string representations of IP addresses instead of Python objects, causing compatibility issues.

Why It Broke

The model_dump() method changed to serialize IP addresses as strings instead of Python objects

Fix Options (Details)

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

pip install pydantic==1.10.19

When NOT to use: Do not use this fix if you require string representation for IP addresses.

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/10594

First fixed release: 1.10.19

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

When NOT to Use This Fix

Do not use this fix if you require string representation for IP addresses.

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
1.10.19	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 model_dump() does not include Python object for IP addresses (Fix)