diff --git a/python/sglang/test/simple_eval_common.py b/python/sglang/test/simple_eval_common.py
index 53243fda9..434c10412 100644
--- a/python/sglang/test/simple_eval_common.py
+++ b/python/sglang/test/simple_eval_common.py
@@ -148,7 +148,7 @@ class ChatCompletionSampler(SamplerBase):
                     reasoning_effort=self.reasoning_effort,
                     extra_body=self.extra_body,
                 )
-                return response.choices[0].message.content
+                return response.choices[0].message.content or ""
             # NOTE: BadRequestError is triggered once for MMMU, please uncomment if you are rerunning MMMU
             except openai.BadRequestError as e:
                 print("Bad Request Error", e)
@@ -161,7 +161,9 @@ class ChatCompletionSampler(SamplerBase):
                 )
                 time.sleep(exception_backoff)
                 trial += 1
-            # unknown error shall throw exception
+        # If all retries are exhausted, return empty string instead of None
+        print(f"All retry attempts exhausted for request. Returning empty response.")
+        return ""
 
 
 QUERY_TEMPLATE_MULTICHOICE = """
@@ -261,7 +263,7 @@ def format_multichoice_question(row):
 def check_equality(sampler: SamplerBase, expr1: str, expr2: str):
     prompt = EQUALITY_TEMPLATE % {"expression1": expr1, "expression2": expr2}
     response = sampler([dict(content=prompt, role="user")])
-    return response.lower().strip() == "yes"
+    return (response or "").lower().strip() == "yes"
 
 
 def _compute_stat(values: list, stat: str):
diff --git a/python/sglang/test/simple_eval_humaneval.py b/python/sglang/test/simple_eval_humaneval.py
index efd03af38..aa77b4d99 100644
--- a/python/sglang/test/simple_eval_humaneval.py
+++ b/python/sglang/test/simple_eval_humaneval.py
@@ -80,6 +80,7 @@ class HumanEval(Eval):
         instruction = "Read the following function signature and docstring, and fully implement the function described. Your response should only contain the code for this function.\n"
 
         def find_code(completion):
+            completion = completion or ""
             pattern = re.compile(r"```python\n(.*?)```", re.DOTALL)
             matches = pattern.findall(completion)
             extracted_answer = matches[0] if len(matches) >= 1 else completion
diff --git a/python/sglang/test/simple_eval_math.py b/python/sglang/test/simple_eval_math.py
index 74c49abe5..37d4b120b 100644
--- a/python/sglang/test/simple_eval_math.py
+++ b/python/sglang/test/simple_eval_math.py
@@ -54,6 +54,7 @@ class MathEval(Eval):
                 sampler._pack_message(content=QUERY_TEMPLATE.format(**row), role="user")
             ]
             response_text = sampler(prompt_messages)
+            response_text = response_text or ""
             match = re.search(ANSWER_PATTERN, response_text)
             extracted_answer = match.group(1) if match else None
             score = float(
diff --git a/python/sglang/test/simple_eval_mmlu.py b/python/sglang/test/simple_eval_mmlu.py
index 36a5c7fe3..a68dbb935 100644
--- a/python/sglang/test/simple_eval_mmlu.py
+++ b/python/sglang/test/simple_eval_mmlu.py
@@ -101,6 +101,7 @@ class MMLUEval(Eval):
                 )
             ]
             response_text = sampler(prompt_messages)
+            response_text = response_text or ""
             match = re.search(ANSWER_PATTERN_MULTICHOICE, response_text)
             extracted_answer = match.group(1) if match else None
             score = 1.0 if extracted_answer == row["Answer"] else 0.0
diff --git a/python/sglang/test/simple_eval_mmmu_vlm.py b/python/sglang/test/simple_eval_mmmu_vlm.py
index 2f64df004..f13cfd687 100644
--- a/python/sglang/test/simple_eval_mmmu_vlm.py
+++ b/python/sglang/test/simple_eval_mmmu_vlm.py
@@ -204,6 +204,7 @@ class MMMUVLMEval(Eval):
 
             # Sample
             response_text = sampler(prompt_messages)
+            response_text = response_text or ""
 
             # Parse and score
             gold = sample["answer"]