FreeNAS

FileNotFoundError: [Errno 2] No such file or directory: 'z': 'z'
  File "middlewared/main.py", line 150, in call_method
    result = await self.middleware.call_method(self, message)
  File "asyncio/coroutines.py", line 109, in __next__
    return self.gen.send(None)
  File "middlewared/main.py", line 895, in call_method
    return await self._call(message['method'], serviceobj, methodobj, params, app=app)
  File "asyncio/coroutines.py", line 109, in __next__
    return self.gen.send(None)
  File "middlewared/main.py", line 863, in _call
    return await methodobj(*args)
  File "asyncio/coroutines.py", line 109, in __next__
    return self.gen.send(None)
  File "middlewared/service.py", line 169, in update
    return await self.do_update(data)
  File "asyncio/coroutines.py", line 109, in __next__
    return self.gen.send(None)
  File "middlewared/schema.py", line 491, in nf
    return await f(*args, **kwargs)
  File "asyncio/coroutines.py", line 109, in __next__
    return self.gen.send(None)
  File "plugins/sysdataset.py", line 70, in do_update
    await self.migrate(config['pool'], data['pool'])
  File "asyncio/coroutines.py", line 109, in __next__
    return self.gen.send(None)
  File "plugins/sysdataset.py", line 309, in migrate
    proc = await Popen(f'zfs list -H -o name {_from}/.system|xargs zfs destroy -r')
  File "asyncio/subprocess.py", line 225, in create_subprocess_exec
    stderr=stderr, **kwds)
  File "asyncio/base_events.py", line 1191, in subprocess_exec
    bufsize, **kwargs)
  File "asyncio/unix_events.py", line 191, in _make_subprocess_transport
    **kwargs)
  File "asyncio/base_subprocess.py", line 39, in __init__
    stderr=stderr, bufsize=bufsize, **kwargs)
  File "asyncio/unix_events.py", line 697, in _start
    universal_newlines=False, bufsize=bufsize, **kwargs)
  File "python3.6/subprocess.py", line 709, in __init__
    restore_signals, start_new_session)
  File "python3.6/subprocess.py", line 1344, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)