Hi Jill - I'm a new user of Houdini and yt (on Windows 10), and I've run into the same problem. I've tried several different ways of installing yt into Houdini Apprentice, both 17.5.425 and 18.0.287, using both conda and pip (separately and from scratch each time). I've also tried both yt 3.4.1 from conda's repository and 3.5.1 from source-forge. No matter what I do I can't get around the fnv_hash DLL installation error. For my current installation attempt, I've created a stand-alone conda environment that I call myYtiniPy27 and I've installed yt into that. The latest yt installs the six and h5py packages (and others too) with it, so I've not installed them separately. I've created a pythonrc.py startup script to add myYtiniPy27 to the path: $ import sys $ sys.path.append('C:\ProgramData\Miniconda2\envs\myYtiniPy27\Lib\site-packages') Houdini runs this at startup. In the Houdini python shell I can successfully import some of the companion modules that get installed with yt (eg. six), so I know the startup script is working. However, when I try to import yt itself I get the same error as others, ie. File "C:\ProgramData\Miniconda2\envs\myYtiniPy27\Lib\site-packages\yt\units\unit_registry.py", line 21, in <module> from yt.utilities.lib.fnv_hash import fnv_hashImportError: DLL load failed: A dynamic link library (DLL) initialization routine failed. I tried your suggestion above for a pip install of fnv_hash but it didn't help. Although sub-packages like six do import OK, others like h5py don't, and give a DLL initialization fail error too. As a hack, I thought I could try just commenting out fnv_hash to get around the problem temporarily. I edited the source file that calls it, unit_registry.py, and recompiled it. This got rid of the fnv_hash import call by yt and therefore the above import error but then that just allowed another module's import error to pop its head up. Because I'm only learning both Houdini and yt at the moment I might continue hacking like this until all the errors go away, hoping of course that I'm only commenting out functions I won't be using, and nothing critical to a learner. In the meantime, have you had any luck tracking down the cause of these problems? Regards Ian