From d0b05b16df3d1ef7cc3e762d8f807394f10a5cbf Mon Sep 17 00:00:00 2001
From: Yiyang Liu <37043548+ianliuy@users.noreply.github.com>
Date: Thu, 16 Apr 2026 14:14:21 -0700
Subject: [PATCH] fix: guard against None thinking param for
 reasoning_effort=none (fixes #25792)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Signed-off-by: Yiyang Liu <37043548+ianliuy@users.noreply.github.com>
---
 litellm/llms/anthropic/chat/transformation.py        | 4 +++-
 litellm/llms/bedrock/chat/converse_transformation.py | 4 +++-
 litellm/llms/databricks/chat/transformation.py       | 4 +++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/litellm/llms/anthropic/chat/transformation.py b/litellm/llms/anthropic/chat/transformation.py
index 6e6078728eb..77bddee9a36 100644
--- a/litellm/llms/anthropic/chat/transformation.py
+++ b/litellm/llms/anthropic/chat/transformation.py
@@ -1088,9 +1088,11 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
             elif param == "thinking":
                 optional_params["thinking"] = value
             elif param == "reasoning_effort" and isinstance(value, str):
-                optional_params["thinking"] = AnthropicConfig._map_reasoning_effort(
+                thinking = AnthropicConfig._map_reasoning_effort(
                     reasoning_effort=value, model=model
                 )
+                if thinking is not None:
+                    optional_params["thinking"] = thinking
                 # For Claude 4.6+ models, effort is controlled via output_config,
                 # not thinking budget_tokens. Map reasoning_effort to output_config.
                 if AnthropicConfig._is_claude_4_6_model(
diff --git a/litellm/llms/bedrock/chat/converse_transformation.py b/litellm/llms/bedrock/chat/converse_transformation.py
index 5d98e1538bd..76a85309fe8 100644
--- a/litellm/llms/bedrock/chat/converse_transformation.py
+++ b/litellm/llms/bedrock/chat/converse_transformation.py
@@ -449,9 +449,11 @@ class AmazonConverseConfig(BaseConfig):
             optional_params.update(reasoning_config)
         else:
             # Anthropic and other models: convert to thinking parameter
-            optional_params["thinking"] = AnthropicConfig._map_reasoning_effort(
+            thinking = AnthropicConfig._map_reasoning_effort(
                 reasoning_effort=reasoning_effort, model=model
             )
+            if thinking is not None:
+                optional_params["thinking"] = thinking
 
     @staticmethod
     def _clamp_thinking_budget_tokens(optional_params: dict) -> None:
diff --git a/litellm/llms/databricks/chat/transformation.py b/litellm/llms/databricks/chat/transformation.py
index 91d6129c3fe..772efe46527 100644
--- a/litellm/llms/databricks/chat/transformation.py
+++ b/litellm/llms/databricks/chat/transformation.py
@@ -330,9 +330,11 @@ class DatabricksConfig(DatabricksBase, OpenAILikeChatConfig, AnthropicConfig):
             )  # unsupported for claude models - if json_schema -> convert to tool call
 
         if "reasoning_effort" in non_default_params and "claude" in model:
-            optional_params["thinking"] = AnthropicConfig._map_reasoning_effort(
+            thinking = AnthropicConfig._map_reasoning_effort(
                 reasoning_effort=non_default_params.get("reasoning_effort"), model=model
             )
+            if thinking is not None:
+                optional_params["thinking"] = thinking
             optional_params.pop("reasoning_effort", None)
         ## handle thinking tokens
         self.update_optional_params_with_thinking_tokens(