diff --git a/llm_server/routes/v1/generate.py b/llm_server/routes/v1/generate.py
index 2abbd4d..923c3e7 100644
--- a/llm_server/routes/v1/generate.py
+++ b/llm_server/routes/v1/generate.py
@@ -96,7 +96,7 @@ def generate():
             else:
                 raise Exception
 
-        log_prompt(client_ip, token, request_json_body['prompt'], backend_response if not backend_err else None, elapsed_time, parameters, dict(request.headers), response.status_code)
+        log_prompt(client_ip, token, request_json_body['prompt'], backend_response if not backend_err else '', elapsed_time, parameters, dict(request.headers), response.status_code)
         return jsonify({
             **response_json_body
         }), 200