Set the ignore_result option for the tasks that don't return values

mayan/apps/sources/tasks.py

@@ -13,7 +13,7 @@ from .models import Source
 logger = logging.getLogger(__name__)
 
 
-@app.task
+@app.task(ignore_result=True)
 def task_upload_document(source_id, file_path, filename=None, use_file_name=False, document_type_id=None, expand=False, metadata_dict_list=None, user_id=None, document_id=None, new_version_data=None, command_line=False, description=None):
     source = Source.objects.get_subclass(pk=source_id)