diff --git a/enterprise/litellm_enterprise/proxy/common_utils/check_batch_cost.py b/enterprise/litellm_enterprise/proxy/common_utils/check_batch_cost.py
index e89501fca6f..66761e84e57 100644
--- a/enterprise/litellm_enterprise/proxy/common_utils/check_batch_cost.py
+++ b/enterprise/litellm_enterprise/proxy/common_utils/check_batch_cost.py
@@ -97,7 +97,11 @@ class CheckBatchCost:
 
         await self._cleanup_stale_managed_objects()
 
-        # Look for all batches that have not yet been processed by CheckBatchCost
+        # Look for all batches that have not yet been processed by CheckBatchCost.
+        # _has_batch_processed_column tracks whether the column exists so the
+        # completion update can omit it on older schemas (avoiding a silent failure
+        # that would cause infinite reprocessing and duplicate cost logging).
+        _has_batch_processed_column = True
         try:
             jobs = await self.prisma_client.db.litellm_managedobjecttable.find_many(
                 where={
@@ -110,6 +114,7 @@ class CheckBatchCost:
             )
         except Exception:
             # Fallback: batch_processed column may not exist on older schemas
+            _has_batch_processed_column = False
             verbose_proxy_logger.warning(
                 "CheckBatchCost: batch_processed column not found, querying without it"
             )
@@ -288,13 +293,15 @@ class CheckBatchCost:
 
                 # mark the job as complete
                 try:
+                    update_data: dict = {
+                        "status": "complete",
+                        "file_object": response.model_dump_json(),
+                    }
+                    if _has_batch_processed_column:
+                        update_data["batch_processed"] = True
                     await self.prisma_client.db.litellm_managedobjecttable.update(
                         where={"id": job.id},
-                        data={
-                            "batch_processed": True,
-                            "status": "complete",
-                            "file_object": response.model_dump_json(),
-                        },
+                        data=update_data,
                     )
                 except Exception as db_err:
                     verbose_proxy_logger.error(
diff --git a/litellm/constants.py b/litellm/constants.py
index 2106c527d96..dbc79b69a67 100644
--- a/litellm/constants.py
+++ b/litellm/constants.py
@@ -1351,9 +1351,9 @@ PROXY_BUDGET_RESCHEDULER_MIN_TIME = int(
     os.getenv("PROXY_BUDGET_RESCHEDULER_MIN_TIME", 597)
 )
 PROXY_BATCH_POLLING_INTERVAL = int(os.getenv("PROXY_BATCH_POLLING_INTERVAL", 3600))
-MAX_OBJECTS_PER_POLL_CYCLE = int(os.getenv("MAX_OBJECTS_PER_POLL_CYCLE", 50))
-MANAGED_OBJECT_STALENESS_CUTOFF_DAYS = int(
-    os.getenv("MANAGED_OBJECT_STALENESS_CUTOFF_DAYS", 7)
+MAX_OBJECTS_PER_POLL_CYCLE = max(1, int(os.getenv("MAX_OBJECTS_PER_POLL_CYCLE", 50)))
+MANAGED_OBJECT_STALENESS_CUTOFF_DAYS = max(
+    1, int(os.getenv("MANAGED_OBJECT_STALENESS_CUTOFF_DAYS", 7))
 )
 # Set PROXY_BATCH_POLLING_ENABLED=false to disable the CheckBatchCost and
 # CheckResponsesCost background polling jobs entirely (e.g. to avoid DB load on
diff --git a/tests/proxy_unit_tests/test_check_batch_cost.py b/tests/proxy_unit_tests/test_check_batch_cost.py
index 36a2f35de1a..94c33669e8b 100644
--- a/tests/proxy_unit_tests/test_check_batch_cost.py
+++ b/tests/proxy_unit_tests/test_check_batch_cost.py
@@ -110,3 +110,49 @@ class TestCheckBatchCost:
         assert "stale_expired" in fallback_where["status"]["not_in"]
         # Fallback must still paginate
         assert calls[1][1]["take"] == MAX_OBJECTS_PER_POLL_CYCLE
+
+    @pytest.mark.asyncio
+    async def test_fallback_completion_update_omits_batch_processed(
+        self, check_batch_cost_instance, mock_prisma_client, mock_llm_router
+    ):
+        """When batch_processed column is absent, completion update must not include it.
+
+        If it did, the update would fail silently, the job would never be marked done,
+        and every subsequent poll cycle would re-log the cost (duplicate billing).
+        """
+        from unittest.mock import patch
+
+        mock_prisma_client.db.litellm_managedobjecttable.update_many = AsyncMock(
+            return_value=0
+        )
+        mock_prisma_client.db.litellm_managedobjecttable.update = AsyncMock()
+
+        mock_job = MagicMock()
+        mock_job.id = "job-fallback-1"
+        mock_job.unified_object_id = "dW5pZmllZF9iYXRjaF9pZA=="  # base64-looking value
+        mock_job.created_by = "user-1"
+
+        # Primary query fails → fallback path
+        mock_prisma_client.db.litellm_managedobjecttable.find_many = AsyncMock(
+            side_effect=[Exception("column batch_processed does not exist"), [mock_job]]
+        )
+
+        # Stub out the heavy per-job processing so we reach the update()
+        with (
+            patch(
+                "litellm.proxy.openai_files_endpoints.common_utils._is_base64_encoded_unified_file_id",
+                return_value=None,  # causes "not a valid unified object id" early-continue
+            ),
+        ):
+            await check_batch_cost_instance.check_batch_cost()
+
+        # Even though the job was skipped (invalid ID), confirm the fallback path was taken
+        # by checking the find_many calls
+        find_calls = mock_prisma_client.db.litellm_managedobjecttable.find_many.call_args_list
+        assert len(find_calls) == 2
+        fallback_where = find_calls[1][1]["where"]
+        assert "batch_processed" not in fallback_where
+
+        # If a completion update were issued, it must not contain batch_processed
+        for call in mock_prisma_client.db.litellm_managedobjecttable.update.call_args_list:
+            assert "batch_processed" not in call[1].get("data", {})