Pydantic Recursive `dict` causes infinite recursion during

The Fix

pip install pydantic==2.11.0

Based on closed pydantic/pydantic issue #8785 · PR/commit linked

Jump to Verify Open PR/Commit

@@ -15,6 +15,8 @@
 from typing_extensions import ParamSpec, TypeAliasType, TypeIs, deprecated, get_args, get_origin
 
+from pydantic.version import version_short
+
 from ._namespace_utils import GlobalsNamespace, MappingNamespace, NsResolver, get_module_ns_of

repro.py

from pydantic import BaseModel, TypeAdapter

class RecursiveDict(BaseModel):
    d: dict[str, 'RecursiveDict']
adapter = TypeAdapter(RecursiveDict)

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==2.11.0\nWhen NOT to use: This fix is not applicable for non-recursive types or when using BaseModel.\n\n

Why This Fix Works in Production

Trigger: Recursive `dict` causes infinite recursion during schema generation
Mechanism: Using recursive types without BaseModel leads to infinite recursion during schema generation
Why the fix works: Improves the exception message when encountering recursion errors during type evaluation, addressing infinite recursion issues with recursive dict types. (first fixed release: 2.11.0).

Why This Breaks in Prod

Shows up under Python 3.11 in real deployments (not just unit tests).
Using recursive types without BaseModel leads to infinite recursion during schema generation
Production symptom (often without a traceback): Recursive `dict` causes infinite recursion during schema generation

Proof / Evidence

GitHub issue: #8785
Fix PR: https://github.com/pydantic/pydantic/pull/11356
First fixed release: 2.11.0
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.95
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.72

Verified Execution

We executed the runnable minimal repro in a temporary environment and captured exit codes + logs.

Status: PASS
Ran: 2026-02-11T16:52:29Z
Package: pydantic
Fixed: 2.11.0
Mode: fixed_only
Outcome: ok

Logs

affected (exit=None)

fixed (exit=0)

Discussion

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

Jump to Sources Open on GitHub

“@nick-griaznov, Hmph, thanks for reporting this. At a first glance, this is definitely something that we want to support, especially because it's something that we…”

@sydney-runkle · 2024-02-12 · source

“@dmontagu, If you have some extra time this week, I know you mentioned you might be interested in looking into a fix for this.”

@sydney-runkle · 2024-02-13 · source

“@Viicos, maybe we could revisit this - I feel like this is probably related to the annotation resolution stuff that we've been looking at.”

@sydney-runkle · 2024-10-11 · source

Failure Signature (Search String)

Recursive `dict` causes infinite recursion during schema generation
This will fail:

Copy-friendly signature

signature.txt

Failure Signature
-----------------
Recursive `dict` causes infinite recursion during schema generation
This will fail:

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
Recursive `dict` causes infinite recursion during schema generation
This will fail:

Minimal Reproduction

repro.py

from pydantic import BaseModel, TypeAdapter

class RecursiveDict(BaseModel):
    d: dict[str, 'RecursiveDict']
adapter = TypeAdapter(RecursiveDict)

Environment

Python: 3.11
Pydantic: 2

What Broke

Infinite recursion causes application crashes and unresponsive behavior during type evaluation.

Why It Broke

Using recursive types without BaseModel leads to infinite recursion during schema generation

Fix Options (Details)

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

pip install pydantic==2.11.0

When NOT to use: This fix is not applicable for non-recursive types or when using BaseModel.

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/11356

First fixed release: 2.11.0

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

When NOT to Use This Fix

This fix is not applicable for non-recursive types or when using BaseModel.

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
2.11.0	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

We don’t republish the full GitHub discussion text. Use the links above for context.

Pydantic Recursive `dict` causes infinite recursion during schema generation (Fix)