I upgraded to ArcGIS Pro 1.4 and I get an error when trying to import arcpy.

[PhilipWoods1]

Getting the following error message when trying to use arcpy.

Runtime error
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "c:\program files\arcgis\pro\Resources\arcpy\arcpy\__init__.py", line 69, in <module>
from arcpy.toolbox import *
File "c:\program files\arcgis\pro\Resources\arcpy\arcpy\toolbox.py", line 688, in <module>
from .wmx import ClearJobReplicationInfo as ClearJobReplicationInfo_wmx
File "c:\program files\arcgis\pro\Resources\arcpy\arcpy\wmx.py", line 29, in <module>
from arcpy import _wmx
File "c:\program files\arcgis\pro\Resources\arcpy\arcpy\_wmx.py", line 9, in <module>
from dateutil import tz
ImportError: cannot import name 'tz'

[MichaelVolz]

Did you upgrade the computer that you had a previous version of Desktop on?  Or is this a new computer with upgraded software?  I ask because maybe you had custom python libraries on your old computer that you forgot needed to be installed on your new computer.

[PhilipWoods1]

No this is a straight update from ArcGIS Pro 1.3 to 1.4. No changes made to the system.

[DanPatterson_Retired]

dateutil - powerful extensions to datetime — dateutil 2.6.0 documentation  perhaps.... 

check your conda distribution to see if it is included

The Python Package Manager—ArcPy Get Started | ArcGIS Desktop 

There is no assumption that the previous packages would be retained... I woul check

[PhilipWoods1 · Accepted solution]

Working through the error message it appears that not all of the dateutil package modules were loaded into the arcgispro-py3 environment. Once this was done everything worked as expected.

[MichaelVolz]

Did you need to rerun or fix the install to get these package modules to install correctly?

[PhilipWoods1]

I just copied the relevant files to the correct location under arcgispro-py3.

[MichaelVolz]

OK but where did you get the files to copy?  Is the location for these files in 10.3 different than in 10.4, so you copied them from the old 10.3 location?

[PhilipWoods1]

In my case I copied files from 

C:\Program Files\ArcGIS\Pro\bin\Python\envs\.pkgs\python-dateutil-2.6.0-py35_0\Lib\site-packages

to

C:\Program Files\ArcGIS\Pro\bin\Python\envs\arcgispro-py3\lib\site-packages