diff --git a/Makefile b/Makefile
index 29d587ec..4954ff83 100644
--- a/Makefile
+++ b/Makefile
@@ -81,5 +81,8 @@ lint-fix:
 format:
 	yapf . --in-place --recursive --parallel --exclude=third_party
 
+test-lite:
+	$(DOCKER_COMPOSE_COMMAND_TASK_RUNNER_LITE) run --build --rm task-runner-lite \
+	pytest -q
 
-style: format lint-fix
\ No newline at end of file
+style: format lint-fix
diff --git a/task-runner/requirements.txt b/task-runner/requirements.txt
index 4eb5bcce..d0f0eff9 100644
--- a/task-runner/requirements.txt
+++ b/task-runner/requirements.txt
@@ -9,3 +9,4 @@ pysocks
 gputil
 pydantic~=2.11.7
 tenacity
+pytest
diff --git a/task-runner/task_runner/task_request_handler.py b/task-runner/task_runner/task_request_handler.py
index a88a268b..d5d7c049 100644
--- a/task-runner/task_runner/task_request_handler.py
+++ b/task-runner/task_runner/task_request_handler.py
@@ -197,17 +197,26 @@ def save_output(
         new_task_status=None,
         force=False,
         output_filename=None,
-    ):
-        _ = self._pack_output(output_filename=output_filename)
-        self._publish_event(events.TaskOutputUploaded(
-            id=self.task_id,
-            machine_id=self.task_runner_uuid,
-            new_status=new_task_status),
-                            force=force)
+    ) -> bool:
+        output_size_bytes = self._pack_output(output_filename=output_filename)
+
+        if output_size_bytes == 0:
+            return False
+
+        self._publish_event(
+            events.TaskOutputUploaded(
+                id=self.task_id,
+                machine_id=self.task_runner_uuid,
+                new_status=new_task_status,
+            ),
+            force=force,
+        )
+
         # Remove the request JSON file to prevent multiple uploads
         # after a successful task data upload
         if os.path.exists(self.request_path):
             os.remove(self.request_path)
+
         return True
 
     def is_task_running(self) -> bool:
@@ -615,21 +624,32 @@ def _execute_request(
         return exit_code, exit_reason
 
     def _pack_output(self, output_filename: Optional[str] = None) -> int:
-        """Compress outputs and store them in the shared drive."""
+        """Compress and upload outputs. If the output size is 0 or not
+        determined (which may happen during unusual conditions) the upload is
+        aborted."""
+        output_size_bytes = 0
+
         if self.task_workdir is None:
             logging.error("Working directory not found.")
-            return
+            return output_size_bytes
 
         output_dir = os.path.join(self.task_workdir, utils.OUTPUT_DIR)
         if not os.path.exists(output_dir):
             logging.error("Output directory not found: %s", output_dir)
-            return
+            return output_size_bytes
 
         output_size_bytes = files.get_dir_size(output_dir)
         logging.info("Output size: %s bytes", output_size_bytes)
 
-        if output_size_bytes is not None:
-            self._post_task_metric(utils.OUTPUT_SIZE, output_size_bytes)
+        if output_size_bytes is None:
+            logging.error("Failed to determine size for output directory: %s",
+                          output_dir)
+            output_size_bytes = 0
+
+        if output_size_bytes == 0:
+            return output_size_bytes
+
+        self._post_task_metric(utils.OUTPUT_SIZE, output_size_bytes)
 
         output_total_files = files.get_dir_total_files(output_dir)
         logging.info("Output total files: %s", output_total_files)
diff --git a/task-runner/tests/unit/test_task_request_handler.py b/task-runner/tests/unit/test_task_request_handler.py
index 57117d43..85f4afd2 100644
--- a/task-runner/tests/unit/test_task_request_handler.py
+++ b/task-runner/tests/unit/test_task_request_handler.py
@@ -133,13 +133,10 @@ def fixture_task_request_handler(
         file_manager=mock.MagicMock(),
     )
 
-    with mock.patch(
-            "task_runner.api_methods_config.get_executer") as get_executer_mock:
-        with mock.patch(
-                "task_runner.utils.files.get_dir_size") as get_dir_size_mock:
-            get_dir_size_mock.return_value = 0
-            get_executer_mock.return_value = MockExecuter
-            yield handler
+    with mock.patch("task_runner.api_methods_config.get_executer",
+                    return_value=MockExecuter), mock.patch.object(
+                        handler, "_pack_output", return_value=1000):
+        yield handler
 
 
 def _setup_mock_task(