diff --git a/dspy/signatures/signature.py b/dspy/signatures/signature.py
index 88812be0c..387b9d771 100644
--- a/dspy/signatures/signature.py
+++ b/dspy/signatures/signature.py
@@ -1,5 +1,6 @@
 import ast
 import inspect
+import logging
 import re
 import types
 import typing
@@ -11,8 +12,9 @@
 from pydantic.fields import FieldInfo
 
 import dsp
-from dspy.signatures.field import InputField, OutputField, new_to_old_field
 from dspy.adapters.image_utils import Image
+from dspy.signatures.field import InputField, OutputField, new_to_old_field
+
 
 def signature_to_template(signature, adapter=None) -> dsp.Template:
     """Convert from new to legacy format."""
@@ -242,8 +244,8 @@ class Signature(BaseModel, metaclass=SignatureMeta):
     @classmethod
     @contextmanager
     def replace(
-        cls: "Signature",
-        new_signature: "Signature",
+        cls,
+        new_signature: "Type[Signature]",
         validate_new_signature: bool = True,
     ) -> typing.Generator[None, None, None]:
         """Replace the signature with an updated version.
@@ -262,16 +264,35 @@ def replace(
                         f"Field '{field}' is missing from the updated signature '{new_signature.__class__}.",
                     )
 
-        class OldSignature(cls, Signature):
+        class OldSignature(cls):
             pass
 
-        replace_fields = ["__doc__", "model_fields", "model_extra", "model_config"]
-        for field in replace_fields:
-            setattr(cls, field, getattr(new_signature, field))
+        def swap_attributes(source: Type[Signature]):
+            unhandled = {}
+
+            for attr in ["__doc__", "__pydantic_fields__", "model_fields", "model_extra", "model_config"]:
+                try:
+                    setattr(cls, attr, getattr(source, attr))
+                except AttributeError as exc:
+                    if attr in ("__pydantic_fields__", "model_fields"):
+                        version = "< 2.10" if attr == "__pydantic_fields__" else ">= 2.10"
+                        logging.debug(f"Model attribute {attr} not replaced, expected with pydantic {version}")
+                        unhandled[attr] = exc
+                    else:
+                        raise exc
+
+            # if neither of the attributes were replaced, raise an error to prevent silent failures
+            if set(unhandled.keys()) >= {"model_fields", "__pydantic_fields__"}:
+                raise ValueError("Failed to replace either model_fields or __pydantic_fields__") from (
+                    unhandled.get("model_fields") or unhandled.get("__pydantic_fields__")
+                )
+
+        swap_attributes(new_signature)
         cls.model_rebuild(force=True)
+
         yield
-        for field in replace_fields:
-            setattr(cls, field, getattr(OldSignature, field))
+
+        swap_attributes(OldSignature)
         cls.model_rebuild(force=True)
 
 
@@ -383,7 +404,7 @@ def _parse_type_node(node, names=None) -> Any:
 
     without using structural pattern matching introduced in Python 3.10.
     """
-    
+
     if names is None:
         names = typing.__dict__
 
@@ -401,7 +422,7 @@ def _parse_type_node(node, names=None) -> Any:
         id_ = node.id
         if id_ in names:
             return names[id_]
-        
+
         for type_ in [int, str, float, bool, list, tuple, dict, Image]:
             if type_.__name__ == id_:
                 return type_
@@ -420,7 +441,7 @@ def _parse_type_node(node, names=None) -> Any:
         keys = [kw.arg for kw in node.keywords]
         values = [kw.value.value for kw in node.keywords]
         return Field(**dict(zip(keys, values)))
-    
+
     if isinstance(node, ast.Attribute) and node.attr == "Image":
         return Image
 
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 98d89e732..23984fa07 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -1,4 +1,7 @@
 black==24.2.0
+datamodel-code-generator==0.26.3
+litellm[proxy]==1.51.0
+pillow==10.4.0
 pre-commit==3.7.0
 pytest==8.3.3
 pytest-env==1.1.3
@@ -6,5 +9,3 @@ pytest-mock==3.12.0
 ruff==0.3.0
 torch==2.2.1
 transformers==4.38.2
-pillow==10.4.0
-litellm[proxy]==1.51.0