diff --git a/litellm/integrations/mavvrik/__init__.py b/litellm/integrations/mavvrik/__init__.py
index ce39976bcc0..2074004012e 100644
--- a/litellm/integrations/mavvrik/__init__.py
+++ b/litellm/integrations/mavvrik/__init__.py
@@ -16,8 +16,6 @@ from datetime import datetime, timedelta
 from datetime import timezone as _tz
 from typing import Optional
 
-import polars as pl
-
 from litellm._logging import verbose_proxy_logger
 from litellm.constants import MAVVRIK_MAX_FETCHED_DATA_RECORDS
 from litellm.integrations.mavvrik.client import Client
diff --git a/litellm/integrations/mavvrik/orchestrator.py b/litellm/integrations/mavvrik/orchestrator.py
index 07822b670e0..679cd12876e 100644
--- a/litellm/integrations/mavvrik/orchestrator.py
+++ b/litellm/integrations/mavvrik/orchestrator.py
@@ -102,8 +102,16 @@ class Orchestrator:
             verbose_logger.warning("Orchestrator: exporting %s → %s", start, end)
 
             for export_date in self._date_range(start, end):
-                await self._export(export_date)
-                await self._advance(export_date)
+                total_bytes = await self._export(export_date)
+                if total_bytes > 0:
+                    await self._advance(export_date)
+                else:
+                    # DB unavailable or no data — raise so the marker does NOT advance.
+                    # Next run will retry this date from the same marker position.
+                    raise RuntimeError(
+                        f"No data streamed for {export_date.isoformat()} "
+                        f"— DB may be unavailable; marker not advanced"
+                    )
 
             verbose_logger.warning("Orchestrator: export complete, last date=%s", end)
 
diff --git a/litellm/integrations/mavvrik/uploader.py b/litellm/integrations/mavvrik/uploader.py
index a7c28b68d2e..d8ad4216f18 100644
--- a/litellm/integrations/mavvrik/uploader.py
+++ b/litellm/integrations/mavvrik/uploader.py
@@ -103,14 +103,19 @@ class Uploader:
         return session_uri
 
     async def _finalize_upload(self, session_uri: str, gzip_bytes: bytes) -> None:
-        """PUT gzip bytes to the GCS session URI to complete the bulk upload."""
+        """PUT gzip bytes to the GCS session URI to complete the bulk upload.
+
+        Sends Content-Range: bytes 0-{last}/{total} per the GCS resumable upload
+        spec so GCS knows the object is complete (consistent with _put_chunk final=True).
+        """
+        total = len(gzip_bytes)
+        content_range = f"bytes 0-{total - 1}/{total}" if total > 0 else "bytes */0"
         resp = await http_request(
             "PUT",
             session_uri,
             headers={
                 "Content-Type": "application/gzip",
-                "Content-Encoding": "gzip",
-                "x-goog-resumable": "stop",
+                "Content-Range": content_range,
             },
             content=gzip_bytes,
             timeout=120.0,
diff --git a/tests/test_litellm/integrations/mavvrik/test_scheduler.py b/tests/test_litellm/integrations/mavvrik/test_scheduler.py
index a8327d96b0d..03e6a121dae 100644
--- a/tests/test_litellm/integrations/mavvrik/test_scheduler.py
+++ b/tests/test_litellm/integrations/mavvrik/test_scheduler.py
@@ -171,8 +171,12 @@ class TestRunExportLoop:
         assert exported_dates == ["2026-04-09", "2026-04-10"]
 
     @pytest.mark.asyncio
-    async def test_skips_upload_when_no_data(self):
-        """When export returns 0 bytes, advance still called (date was processed)."""
+    async def test_does_not_advance_when_no_data(self):
+        """When export returns 0 bytes, marker is NOT advanced — prevents silent data loss.
+
+        0 bytes means DB was unavailable or no data for that date.
+        Raising ensures the marker stays put so the date is retried next run.
+        """
         orc = _make_orchestrator()
 
         orc._client.register = AsyncMock(return_value="2026-04-09")
@@ -188,8 +192,10 @@ class TestRunExportLoop:
         ):
             await orc.run()
 
-        # advance_marker always called — even for empty dates
-        orc._client.advance_marker.assert_called_once()
+        # advance_marker must NOT be called when 0 bytes exported
+        orc._client.advance_marker.assert_not_called()
+        # error reported to Mavvrik so the failure is visible
+        orc._client.report_error.assert_called_once()
 
     @pytest.mark.asyncio
     async def test_reports_error_on_pipeline_failure(self):