Hello,

Dashboard (CPU & Memory) and Reporting do not show values.

Error message on boot:

The following alert has been cleared:

• Failed to check for alert VolumeStatus:
  Traceback (most recent call last):
  File "/usr/local/lib/python3.8/ site-packages/middlewared/ plugins/alert.py", line 706, in __run_source
  alerts = (await alert_source.check()) or []
  File "/usr/local/lib/python3.8/ site-packages/middlewared/ alert/source/volume_status.py" , line 31, in check
  for vdev in await self.middleware.call("pool. flatten_topology", pool["topology"]):
  File "/usr/local/lib/python3.8/ site-packages/middlewared/ main.py", line 1233, in call
  return await self._call(
  File "/usr/local/lib/python3.8/ site-packages/middlewared/ main.py", line 1202, in _call
  return await self.run_in_executor(prepared_ call.executor, methodobj, *prepared_call.args)
  File "/usr/local/lib/python3.8/ site-packages/middlewared/ main.py", line 1106, 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 431, in flatten_topology
  d = deque(sum(topology.values(), []))
  AttributeError: 'NoneType' object has no attribute 'values'