From 9d44d0a5e5b267a3ebfad872746e483b2b2d93bb Mon Sep 17 00:00:00 2001
From: Vinicius Brasil <vini@hey.com>
Date: Tue, 16 Jun 2026 11:00:07 -0700
Subject: [PATCH] Serialize concrete Pydantic subclasses (#6187)

---
 lib/crewai/src/crewai/utilities/serialization.py |  2 +-
 lib/crewai/tests/utilities/test_serialization.py | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/lib/crewai/src/crewai/utilities/serialization.py b/lib/crewai/src/crewai/utilities/serialization.py
index 1b9e76588..8bc38b6f8 100644
--- a/lib/crewai/src/crewai/utilities/serialization.py
+++ b/lib/crewai/src/crewai/utilities/serialization.py
@@ -99,7 +99,7 @@ def to_serializable(
     if isinstance(obj, BaseModel):
         try:
             return to_serializable(
-                obj=obj.model_dump(mode="json", exclude=exclude),
+                obj=obj.model_dump(mode="json", exclude=exclude, serialize_as_any=True),
                 max_depth=max_depth,
                 _current_depth=_current_depth + 1,
                 _ancestors=new_ancestors,
diff --git a/lib/crewai/tests/utilities/test_serialization.py b/lib/crewai/tests/utilities/test_serialization.py
index 8ec68ead8..93817f285 100644
--- a/lib/crewai/tests/utilities/test_serialization.py
+++ b/lib/crewai/tests/utilities/test_serialization.py
@@ -21,6 +21,10 @@ class Person(BaseModel):
     skills: List[str]
 
 
+class Container(BaseModel):
+    payload: BaseModel | None = None
+
+
 @dataclass
 class DataclassPerson:
     name: str
@@ -114,6 +118,16 @@ def test_pydantic_model_serialization():
     )
 
 
+def test_polymorphic_field_serializes_concrete_subclass():
+    container = Container(
+        payload=Address(street="1 Main", city="Tech City", country="Pythonia")
+    )
+
+    assert to_serializable(container) == {
+        "payload": {"street": "1 Main", "city": "Tech City", "country": "Pythonia"}
+    }
+
+
 def test_dataclass_serialization_recurses_into_nested_values():
     person = DataclassPerson(
         name="Ada",