self.run_in_executor(prepared_call.executor, methodobj, *prepared_call.args) File "/usr/local/lib/python3.8/site-packages/middlewared/main.py", line 1110, in run_in_executor return await loop.run_in_executor(pool, functools.partial(method, *args, **kwargs)) File "/usr/local/lib/python3.8/site-packages/middlewared/utils/io_thread_pool_executor.py", line 25, in run result = self.fn(*self.args, **self.kwargs) File "/usr/local/lib/python3.8/site-packages/middlewared/plugins/pool.py", line 438, in flatten_topology d = deque(sum(topology.values(), [])) AttributeError: 'NoneType' object has no attribute 'values'