NotInitialized error when importing arcpy

[mws2459]

import arcpy

Traceback (most recent call last):
File "<pyshell#0>", line 1, in
import arcpy
File "C:\Program Files (x86)\ArcGIS\Desktop10.4\ArcPy\arcpy__init__.py", line 22, in
from arcpy.geoprocessing import gp
File "C:\Program Files (x86)\ArcGIS\Desktop10.4\ArcPy\arcpy\geoprocessing__init__.py", line 14, in
from _base import *
File "C:\Program Files (x86)\ArcGIS\Desktop10.4\ArcPy\arcpy\geoprocessing_base.py", line 608, in
env = GPEnvironments(gp)
File "C:\Program Files (x86)\ArcGIS\Desktop10.4\ArcPy\arcpy\geoprocessing_base.py", line 605, in GPEnvironments
return GPEnvironment(geoprocessor)
File "C:\Program Files (x86)\ArcGIS\Desktop10.4\ArcPy\arcpy\geoprocessing_base.py", line 561, in init
self._refresh()
File "C:\Program Files (x86)\ArcGIS\Desktop10.4\ArcPy\arcpy\geoprocessing_base.py", line 563, in _refresh
envset = (set(env for env in self._gp.listEnvironments()))
RuntimeError: NotInitialized