fix(proxy): include litellm_call_id in LLM API exception logs

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm/proxy/common_request_processing.py

@@ -1322,13 +1322,19 @@ def _has_attribute_error_in_chain(exc: Exception) -> bool:
 _CLIENT_DISCONNECT_DETAIL: Final = "Client disconnected the request"
 
 
-def _log_llm_api_exception(e: Exception) -> None:
+def _log_llm_api_exception(e: Exception, litellm_call_id: str | None) -> None:
     if getattr(e, "status_code", None) == 499 and getattr(e, "detail", None) == _CLIENT_DISCONNECT_DETAIL:
         verbose_proxy_logger.info(
-            "litellm.proxy.proxy_server._handle_llm_api_exception(): client disconnected, upstream LLM request cancelled"
+            "litellm.proxy.proxy_server._handle_llm_api_exception(): client disconnected, upstream LLM request cancelled - litellm_call_id=%s",
+            litellm_call_id,
         )
         return
-    verbose_proxy_logger.exception("litellm.proxy.proxy_server._handle_llm_api_exception(): Exception occured - %s", e)
+    verbose_proxy_logger.exception(
+        "litellm.proxy.proxy_server._handle_llm_api_exception(): Exception occured - litellm_call_id=%s - %s",
+        litellm_call_id,
+        e,
+        extra={"litellm_call_id": litellm_call_id},
+    )
 
 
 async def _cancel_llm_call_on_client_disconnect(
@@ -3046,7 +3052,15 @@ class ProxyBaseLLMRequestProcessing:
         version: str | None = None,
     ):
         """Raises ProxyException (OpenAI API compatible) if an exception is raised"""
-        _log_llm_api_exception(e)
+        _logging_obj_for_call_id: Final[LiteLLMLoggingObj | None] = self.data.get("litellm_logging_obj", None)
+        _log_llm_api_exception(
+            e,
+            (
+                _logging_obj_for_call_id.litellm_call_id
+                if _logging_obj_for_call_id
+                else self.data.get("litellm_call_id")
+            ),
+        )
         # Allow callbacks to transform the error response
         transformed_exception: Final = await proxy_logging_obj.post_call_failure_hook(
             user_api_key_dict=user_api_key_dict,

tests/test_litellm/proxy/test_common_request_processing.py

@@ -6637,3 +6637,59 @@ async def test_a_broken_hook_does_not_replace_the_real_error_with_its_own_bug():
     error_frame = json.loads(collected[-2].decode().removeprefix("data: ").strip())
     assert error_frame["error"]["message"] == "rate limited"
     assert "audit backend" not in collected[-2].decode()
+
+
+class TestErrorLogCarriesCallId:
+    """Regression for LIT-5856 / #37532: the ERROR line emitted for a failed LLM
+    request must carry the same litellm_call_id the client got back in the
+    x-litellm-call-id response header, so a logged exception can be correlated
+    with a specific request."""
+
+    async def _invoke(self, data: dict) -> None:
+        from litellm.proxy._types import ProxyException, UserAPIKeyAuth
+
+        processor = ProxyBaseLLMRequestProcessing(data=data)
+        proxy_logging_obj = MagicMock()
+        proxy_logging_obj.post_call_failure_hook = AsyncMock(return_value=None)
+        proxy_logging_obj.post_call_response_headers_hook = AsyncMock(return_value={})
+        with pytest.raises(ProxyException):
+            await processor._handle_llm_api_exception(
+                e=ValueError("upstream blew up"),
+                user_api_key_dict=UserAPIKeyAuth(api_key="sk-test"),
+                proxy_logging_obj=proxy_logging_obj,
+            )
+
+    async def test_call_id_from_logging_obj_is_logged(self, caplog):
+        call_id = str(uuid.uuid4())
+        logging_obj = MagicMock()
+        logging_obj.litellm_call_id = call_id
+        with caplog.at_level("ERROR", logger="LiteLLM Proxy"):
+            await self._invoke({"litellm_logging_obj": logging_obj, "litellm_call_id": "stale-id"})
+
+        record = next(r for r in caplog.records if r.levelname == "ERROR")
+        assert record.litellm_call_id == call_id
+        assert call_id in record.getMessage()
+
+    async def test_call_id_falls_back_to_request_data(self, caplog):
+        call_id = str(uuid.uuid4())
+        with caplog.at_level("ERROR", logger="LiteLLM Proxy"):
+            await self._invoke({"litellm_call_id": call_id})
+
+        record = next(r for r in caplog.records if r.levelname == "ERROR")
+        assert record.litellm_call_id == call_id
+        assert call_id in record.getMessage()
+
+    def test_client_disconnect_log_carries_call_id(self, caplog):
+        from litellm.proxy.common_request_processing import (
+            _CLIENT_DISCONNECT_DETAIL,
+            _log_llm_api_exception,
+        )
+
+        call_id = str(uuid.uuid4())
+        with caplog.at_level("INFO", logger="LiteLLM Proxy"):
+            _log_llm_api_exception(
+                HTTPException(status_code=499, detail=_CLIENT_DISCONNECT_DETAIL),
+                call_id,
+            )
+
+        assert call_id in caplog.records[-1].getMessage()