diff --git a/lilac/tasks.py b/lilac/tasks.py
index 43a453dc..955f5dab 100644
--- a/lilac/tasks.py
+++ b/lilac/tasks.py
@@ -28,11 +28,18 @@
 TaskFn = Union[Callable[..., Any], Callable[..., Awaitable[Any]]]
 
 
+class CancellationError(Exception):
+  """An error raised when a task is cancelled."""
+
+  pass
+
+
 class TaskStatus(str, Enum):
   """Enum holding a tasks status."""
 
   PENDING = 'pending'
   COMPLETED = 'completed'
+  CANCELLED = 'cancelled'
   ERROR = 'error'
 
 
@@ -127,6 +134,8 @@ def launch_task(self, task_id: TaskId, run_fn: Callable[..., Any]) -> None:
     def _wrapper() -> None:
       try:
         run_fn()
+      except CancellationError:
+        self.set_cancelled(task_id)
       except Exception as e:
         log(e)
         self.set_error(task_id, str(e))
@@ -157,6 +166,12 @@ def report_progress(self, task_id: TaskId, progress: int) -> None:
     elapsed = pretty_timedelta(timedelta(seconds=elapsed_sec))
     task.details = f'{progress:,}/{task.total_len:,} [{elapsed} {ex_per_sec:,.2f} ex/s]'
 
+  def set_cancelled(self, task_id: TaskId) -> None:
+    """Mark a task as cancelled."""
+    task = self._task_info[task_id]
+    task.status = TaskStatus.CANCELLED
+    task.end_timestamp = datetime.now().isoformat()
+
   def set_error(self, task_id: TaskId, error: str) -> None:
     """Mark a task as errored."""
     task = self._task_info[task_id]
@@ -212,15 +227,19 @@ def progress_reporter(it: Iterator[TProgress]) -> Iterator[TProgress]:
     try:
       for item in tqdm(it, initial=progress, total=task_info.total_len, desc=task_info.description):
         if task_manager._task_stopped[task_id]:
-          raise AssertionError('Task cancelled successfully!')
+          raise CancellationError('Task cancelled successfully!')
         progress += 1
         if progress % 100 == 0:
           task_manager.report_progress(task_id, progress)
         yield item
+    except CancellationError:
+      task_manager.set_cancelled(task_id)
+      raise
     except Exception as e:
       task_manager.set_error(task_id, str(e))
       raise e
-    task_manager.set_completed(task_id)
+    else:
+      task_manager.set_completed(task_id)
 
   return progress_reporter