diff --git a/rag/graphrag/general/extractor.py b/rag/graphrag/general/extractor.py
index 3328604b67..2c0dae54d0 100644
--- a/rag/graphrag/general/extractor.py
+++ b/rag/graphrag/general/extractor.py
@@ -62,11 +62,26 @@ class Extractor:
         self._language = language
         self._entity_types = entity_types or DEFAULT_ENTITY_TYPES
 
+    @staticmethod
+    def _normalize_response_text(response):
+        if isinstance(response, (list, tuple)):
+            response = response[0] if response else ""
+        if response is None:
+            return ""
+        return response if isinstance(response, str) else str(response)
+
+    @staticmethod
+    def _is_truncated_cache(response):
+        return len((response or "").strip()) <= 1
+
     @timeout(60 * 20)
     def _chat(self, system, history, gen_conf={}, task_id=""):
         hist = deepcopy(history)
         conf = deepcopy(gen_conf)
         response = get_llm_cache(self._llm.llm_name, system, hist, conf)
+        response = self._normalize_response_text(response)
+        if self._is_truncated_cache(response):
+            response = ""
         if response:
             return response
         _, system_msg = message_fit_in([{"role": "system", "content": system}], int(self._llm.max_length * 0.92))
@@ -78,10 +93,12 @@ class Extractor:
                     raise TaskCanceledException(f"Task {task_id} was cancelled")
             try:
                 response = asyncio.run(self._llm.async_chat(system_msg[0]["content"], hist, conf))
-                response = re.sub(r"^.*</think>", "", response[0], flags=re.DOTALL)
+                response = self._normalize_response_text(response)
+                response = re.sub(r"^.*</think>", "", response, flags=re.DOTALL)
                 if response.find("**ERROR**") >= 0:
                     raise Exception(response)
-                set_llm_cache(self._llm.llm_name, system, response, history, gen_conf)
+                if not self._is_truncated_cache(response):
+                    set_llm_cache(self._llm.llm_name, system, response, history, gen_conf)
                 break
             except Exception as e:
                 logging.exception(e)