diff --git a/django/aiservice/aiservice/llm.py b/django/aiservice/aiservice/llm.py
index e41831830..ceeb6ea71 100644
--- a/django/aiservice/aiservice/llm.py
+++ b/django/aiservice/aiservice/llm.py
@@ -198,6 +198,17 @@ class LLMClient:
         response = await self.anthropic_client.messages.create(**kwargs)  # type: ignore[union-attr]
         content = "".join(block.text for block in response.content if hasattr(block, "text"))
 
+        if not content:
+            logger.warning(
+                "Anthropic returned empty content: model=%s, stop_reason=%s",
+                llm.name,
+                response.stop_reason,
+            )
+            raise LLMOutputUnparseable(
+                f"Empty response from {llm.name} (stop_reason={response.stop_reason})",
+                cost=calculate_llm_cost(response, llm),
+            )
+
         return LLMResponse(
             content=content,
             usage=LLMUsage(input_tokens=response.usage.input_tokens, output_tokens=response.usage.output_tokens),
@@ -216,8 +227,21 @@ class LLMClient:
                 model=llm.name, messages=messages, max_tokens=max_tokens
             )
 
+        content = response.choices[0].message.content if response.choices else None
+        if not content:
+            finish = response.choices[0].finish_reason if response.choices else "unknown"
+            logger.warning(
+                "OpenAI returned empty content: model=%s, finish_reason=%s",
+                llm.name,
+                finish,
+            )
+            raise LLMOutputUnparseable(
+                f"Empty response from {llm.name} (finish_reason={finish})",
+                cost=calculate_llm_cost(response, llm),
+            )
+
         return LLMResponse(
-            content=response.choices[0].message.content or "",
+            content=content,
             usage=LLMUsage(
                 input_tokens=response.usage.prompt_tokens if response.usage else 0,
                 output_tokens=response.usage.completion_tokens if response.usage else 0,
diff --git a/django/aiservice/core/languages/java/optimizer.py b/django/aiservice/core/languages/java/optimizer.py
index 583703f38..24970e6c0 100644
--- a/django/aiservice/core/languages/java/optimizer.py
+++ b/django/aiservice/core/languages/java/optimizer.py
@@ -17,7 +17,7 @@ from openai.types.chat import ChatCompletionSystemMessageParam, ChatCompletionUs
 from aiservice.analytics.posthog import ph
 from aiservice.common_utils import validate_trace_id
 from aiservice.env_specific import debug_log_sensitive_data, debug_log_sensitive_data_from_callable
-from aiservice.llm import llm_client
+from aiservice.llm import LLMOutputUnparseable, llm_client
 from aiservice.llm_models import LLM, OPTIMIZE_MODEL
 from authapp.auth import AuthenticatedRequest
 from authapp.user import get_user_by_id
@@ -119,6 +119,9 @@ async def optimize_java_code_single(
             python_version="N/A",  # Not applicable for Java
             context=obs_context,
         )
+    except LLMOutputUnparseable as e:
+        debug_log_sensitive_data(f"Empty LLM response for Java source:\n{source_code}")
+        return None, e.cost, optimize_model.name
     except Exception:
         debug_log_sensitive_data(f"Failed to generate code for Java source:\n{source_code}")
         return None, None, optimize_model.name
diff --git a/django/aiservice/core/languages/java/optimizer_lp.py b/django/aiservice/core/languages/java/optimizer_lp.py
index 0e37856b6..259eb15dc 100644
--- a/django/aiservice/core/languages/java/optimizer_lp.py
+++ b/django/aiservice/core/languages/java/optimizer_lp.py
@@ -17,7 +17,7 @@ from openai.types.chat import ChatCompletionSystemMessageParam, ChatCompletionUs
 
 from aiservice.analytics.posthog import ph
 from aiservice.env_specific import debug_log_sensitive_data, debug_log_sensitive_data_from_callable
-from aiservice.llm import llm_client
+from aiservice.llm import LLMOutputUnparseable, llm_client
 from aiservice.llm_models import OPTIMIZE_MODEL
 from aiservice.validators.java_validator import validate_java_syntax
 from core.languages.java.optimizer import is_multi_context_java
@@ -166,6 +166,9 @@ Here is the code to optimize:
             python_version=f"Java {language_version}",
             context=obs_context,
         )
+    except LLMOutputUnparseable as e:
+        debug_log_sensitive_data(f"Empty LLM response for source:\n{source_code}")
+        return None, e.cost, optimize_model.name
     except Exception:
         debug_log_sensitive_data(f"Failed to generate code for source:\n{source_code}")
         return None, None, optimize_model.name
diff --git a/django/aiservice/core/languages/js_ts/optimizer.py b/django/aiservice/core/languages/js_ts/optimizer.py
index d0e6bcee7..27edcdfe4 100644
--- a/django/aiservice/core/languages/js_ts/optimizer.py
+++ b/django/aiservice/core/languages/js_ts/optimizer.py
@@ -19,7 +19,7 @@ from aiservice.analytics.posthog import ph
 from aiservice.common.markdown_utils import split_markdown_code
 from aiservice.common_utils import validate_trace_id
 from aiservice.env_specific import debug_log_sensitive_data, debug_log_sensitive_data_from_callable
-from aiservice.llm import llm_client
+from aiservice.llm import LLMOutputUnparseable, llm_client
 from aiservice.llm_models import LLM, OPTIMIZE_MODEL
 from aiservice.validators.javascript_validator import validate_javascript_syntax, validate_typescript_syntax
 from authapp.auth import AuthenticatedRequest
@@ -155,6 +155,9 @@ You MUST output the target file. You may also output helper files if you optimiz
             python_version=language_version,  # Reusing python_version field for language version
             context=obs_context,
         )
+    except LLMOutputUnparseable as e:
+        debug_log_sensitive_data(f"Empty LLM response for source:\n{source_code}")
+        return None, e.cost, optimize_model.name
     except Exception:
         debug_log_sensitive_data(f"Failed to generate code for source:\n{source_code}")
         return None, None, optimize_model.name
diff --git a/django/aiservice/core/languages/js_ts/optimizer_lp.py b/django/aiservice/core/languages/js_ts/optimizer_lp.py
index b4a73382e..2c6ca6a9b 100644
--- a/django/aiservice/core/languages/js_ts/optimizer_lp.py
+++ b/django/aiservice/core/languages/js_ts/optimizer_lp.py
@@ -18,7 +18,7 @@ from openai.types.chat import ChatCompletionSystemMessageParam, ChatCompletionUs
 from aiservice.analytics.posthog import ph
 from aiservice.common.markdown_utils import split_markdown_code
 from aiservice.env_specific import debug_log_sensitive_data, debug_log_sensitive_data_from_callable
-from aiservice.llm import llm_client
+from aiservice.llm import LLMOutputUnparseable, llm_client
 from aiservice.llm_models import OPTIMIZE_MODEL
 from aiservice.validators.javascript_validator import validate_javascript_syntax, validate_typescript_syntax
 from core.languages.js_ts.context_helpers import is_multi_context_js, is_multi_context_ts
@@ -167,6 +167,9 @@ Here is the code to optimize:
             python_version=language_version,  # Reusing python_version field for language version
             context=obs_context,
         )
+    except LLMOutputUnparseable as e:
+        debug_log_sensitive_data(f"Empty LLM response for source:\n{source_code}")
+        return None, e.cost, optimize_model.name
     except Exception:
         debug_log_sensitive_data(f"Failed to generate code for source:\n{source_code}")
         return None, None, optimize_model.name
diff --git a/django/aiservice/core/languages/python/jit_rewrite/jit_rewrite.py b/django/aiservice/core/languages/python/jit_rewrite/jit_rewrite.py
index 163209785..0a7835bc6 100644
--- a/django/aiservice/core/languages/python/jit_rewrite/jit_rewrite.py
+++ b/django/aiservice/core/languages/python/jit_rewrite/jit_rewrite.py
@@ -16,7 +16,7 @@ from aiservice.analytics.posthog import ph
 from aiservice.background import fire_and_forget
 from aiservice.common_utils import parse_python_version, validate_trace_id
 from aiservice.env_specific import debug_log_sensitive_data, debug_log_sensitive_data_from_callable
-from aiservice.llm import llm_client
+from aiservice.llm import LLMOutputUnparseable, llm_client
 from aiservice.llm_models import LLM, OPTIMIZE_MODEL
 from authapp.auth import AuthenticatedRequest
 from authapp.user import get_user_by_id
@@ -74,6 +74,9 @@ async def jit_rewrite_python_code_single(
             python_version=python_version_str,
             context=obs_context,
         )
+    except LLMOutputUnparseable as e:
+        debug_log_sensitive_data(f"Empty LLM response for source:\n{ctx.source_code}")
+        return None, e.cost, jit_rewrite_model.name
     except Exception:
         debug_log_sensitive_data(f"Failed to generate code for source:\n{ctx.source_code}")
         return None, None, jit_rewrite_model.name
diff --git a/django/aiservice/core/languages/python/optimizer/optimizer.py b/django/aiservice/core/languages/python/optimizer/optimizer.py
index 70227feeb..ee2688dfa 100644
--- a/django/aiservice/core/languages/python/optimizer/optimizer.py
+++ b/django/aiservice/core/languages/python/optimizer/optimizer.py
@@ -15,7 +15,7 @@ from aiservice.analytics.posthog import ph
 from aiservice.background import fire_and_forget
 from aiservice.common_utils import parse_python_version, validate_trace_id
 from aiservice.env_specific import debug_log_sensitive_data, debug_log_sensitive_data_from_callable
-from aiservice.llm import llm_client
+from aiservice.llm import LLMOutputUnparseable, llm_client
 from aiservice.llm_models import LLM, OPTIMIZE_MODEL
 from authapp.user import get_user_by_id
 from core.languages.python.optimizer.context_utils.optimizer_context import BaseOptimizerContext
@@ -82,6 +82,9 @@ async def generate_optimization_candidate(
             python_version=python_version_str,
             context=obs_context,
         )
+    except LLMOutputUnparseable as e:
+        debug_log_sensitive_data(f"Empty LLM response for source:\n{ctx.source_code}")
+        return None, e.cost, optimize_model.name
     except Exception:
         debug_log_sensitive_data(f"Failed to generate code for source:\n{ctx.source_code}")
         return None, None, optimize_model.name
diff --git a/django/aiservice/core/languages/python/optimizer/optimizer_line_profiler.py b/django/aiservice/core/languages/python/optimizer/optimizer_line_profiler.py
index d0c86bd65..1d059c41f 100644
--- a/django/aiservice/core/languages/python/optimizer/optimizer_line_profiler.py
+++ b/django/aiservice/core/languages/python/optimizer/optimizer_line_profiler.py
@@ -13,7 +13,7 @@ from aiservice.background import fire_and_forget
 from aiservice.common.markdown_utils import split_markdown_code
 from aiservice.common_utils import parse_python_version, validate_trace_id
 from aiservice.env_specific import debug_log_sensitive_data, debug_log_sensitive_data_from_callable
-from aiservice.llm import llm_client
+from aiservice.llm import LLMOutputUnparseable, llm_client
 from aiservice.llm_models import OPTIMIZE_MODEL
 from aiservice.validators.javascript_validator import validate_javascript_syntax, validate_typescript_syntax
 from core.languages.java.optimizer_lp import optimize_java_code_line_profiler
@@ -90,6 +90,9 @@ async def optimize_python_code_line_profiler_single(
             python_version=python_version_str,
             context=obs_context,
         )
+    except LLMOutputUnparseable as e:
+        debug_log_sensitive_data(f"Empty LLM response for source:\n{ctx.source_code}")
+        return None, e.cost, optimize_model.name
     except Exception:
         debug_log_sensitive_data(f"Failed to generate code for source:\n{ctx.source_code}")
         return None, None, optimize_model.name