diff --git a/litellm/integrations/langfuse.py b/litellm/integrations/langfuse.py
index 0217f7458d9..73a8ed0d94f 100644
--- a/litellm/integrations/langfuse.py
+++ b/litellm/integrations/langfuse.py
@@ -144,6 +144,10 @@ class LangFuseLogger:
                 f"Langfuse Logging - Enters logging function for model {kwargs}"
             )
 
+            # set default values for input/output for langfuse logging
+            input = None
+            output = None
+
             litellm_params = kwargs.get("litellm_params", {})
             litellm_call_id = kwargs.get("litellm_call_id", None)
             metadata = (
diff --git a/litellm/proxy/proxy_config.yaml b/litellm/proxy/proxy_config.yaml
index 7a8bd9535df..f7e5a894f01 100644
--- a/litellm/proxy/proxy_config.yaml
+++ b/litellm/proxy/proxy_config.yaml
@@ -34,4 +34,4 @@ general_settings:
   max_response_size_mb: 10
 
 litellm_settings:
-  callbacks: ["otel"]
\ No newline at end of file
+  success_callback: ["langfuse"]
\ No newline at end of file