diff --git a/libs/core/langchain_core/language_models/chat_models.py b/libs/core/langchain_core/language_models/chat_models.py
index 3b0a626d237..c5e7b43cebf 100644
--- a/libs/core/langchain_core/language_models/chat_models.py
+++ b/libs/core/langchain_core/language_models/chat_models.py
@@ -11,22 +11,9 @@ from abc import ABC, abstractmethod
 from collections.abc import AsyncIterator, Iterator, Sequence
 from functools import cached_property
 from operator import itemgetter
-from typing import (
-    TYPE_CHECKING,
-    Any,
-    Callable,
-    Literal,
-    Optional,
-    Union,
-    cast,
-)
+from typing import TYPE_CHECKING, Any, Callable, Literal, Optional, Union, cast
 
-from pydantic import (
-    BaseModel,
-    ConfigDict,
-    Field,
-    model_validator,
-)
+from pydantic import BaseModel, ConfigDict, Field, model_validator
 from typing_extensions import override
 
 from langchain_core._api import deprecated
@@ -654,6 +641,34 @@ class BaseChatModel(BaseLanguageModel[BaseMessage], ABC):
     def _combine_llm_outputs(self, llm_outputs: list[Optional[dict]]) -> dict:  # noqa: ARG002
         return {}
 
+    def _convert_cached_generations(self, cache_val: list) -> list[ChatGeneration]:
+        """Convert cached Generation objects to ChatGeneration objects.
+
+        Handle case where cache contains Generation objects instead of
+        ChatGeneration objects. This can happen due to serialization/deserialization
+        issues or legacy cache data (see #22389).
+
+        Args:
+            cache_val: List of cached generation objects.
+
+        Returns:
+            List of ChatGeneration objects.
+        """
+        converted_generations = []
+        for gen in cache_val:
+            if isinstance(gen, Generation) and not isinstance(gen, ChatGeneration):
+                # Convert Generation to ChatGeneration by creating AIMessage
+                # from the text content
+                chat_gen = ChatGeneration(
+                    message=AIMessage(content=gen.text),
+                    generation_info=gen.generation_info,
+                )
+                converted_generations.append(chat_gen)
+            else:
+                # Already a ChatGeneration or other expected type
+                converted_generations.append(gen)
+        return converted_generations
+
     def _get_invocation_params(
         self,
         stop: Optional[list[str]] = None,
@@ -1011,25 +1026,7 @@ class BaseChatModel(BaseLanguageModel[BaseMessage], ABC):
                 prompt = dumps(messages)
                 cache_val = llm_cache.lookup(prompt, llm_string)
                 if isinstance(cache_val, list):
-                    # Handle case where cache contains Generation objects instead of
-                    # ChatGeneration objects
-                    # This can happen due to serialization/deserialization issues or
-                    # legacy cache data
-                    converted_generations = []
-                    for gen in cache_val:
-                        if isinstance(gen, Generation) and not isinstance(
-                            gen, ChatGeneration
-                        ):
-                            # Convert Generation to ChatGeneration by creating AIMessage
-                            # from the text content
-                            chat_gen = ChatGeneration(
-                                message=AIMessage(content=gen.text),
-                                generation_info=gen.generation_info,
-                            )
-                            converted_generations.append(chat_gen)
-                        else:
-                            # Already a ChatGeneration or other expected type
-                            converted_generations.append(gen)
+                    converted_generations = self._convert_cached_generations(cache_val)
                     return ChatResult(generations=converted_generations)
             elif self.cache is None:
                 pass
@@ -1102,25 +1099,7 @@ class BaseChatModel(BaseLanguageModel[BaseMessage], ABC):
                 prompt = dumps(messages)
                 cache_val = await llm_cache.alookup(prompt, llm_string)
                 if isinstance(cache_val, list):
-                    # Handle case where cache contains Generation objects instead of
-                    # ChatGeneration objects
-                    # This can happen due to serialization/deserialization issues or
-                    # legacy cache data
-                    converted_generations = []
-                    for gen in cache_val:
-                        if isinstance(gen, Generation) and not isinstance(
-                            gen, ChatGeneration
-                        ):
-                            # Convert Generation to ChatGeneration by creating AIMessage
-                            # from the text content
-                            chat_gen = ChatGeneration(
-                                message=AIMessage(content=gen.text),
-                                generation_info=gen.generation_info,
-                            )
-                            converted_generations.append(chat_gen)
-                        else:
-                            # Already a ChatGeneration or other expected type
-                            converted_generations.append(gen)
+                    converted_generations = self._convert_cached_generations(cache_val)
                     return ChatResult(generations=converted_generations)
             elif self.cache is None:
                 pass