Further to my above comments, I've done some more investigations. When yt is installed by conda into my standalone virtual environment myYtiniPy25, a total of 37 packages (yt included) are installed. My Houdini start up script adds this virtualenv to the path. When in Houdini, I've tested importing each of these packages one by one by using the import command in the python shell. The results are as follows (they are the same whether it's 17.5 and 18.0). These packages import with no problems and no error messages: backports, backports.functools_lru_cache, backports.shutil_get_terminal_size, backports_abc, colorama, cycler, decorator, functools32, ipython_genutils, linecache2, matplotlib, mpmath, numpy, pathlib2, pickleshare, prompt_toolkit, pygments, pyparsing, pyreadline, pytz, scandir, simplegeneric, singledispatch, sip, six, sympy, tornado, traceback2, traitlets, unittest2, wcwidth, win_unicode_console, zlib These packages throw a MSVC++ runtime error R6034 dialog but python gives no error message (and if I try the import again, it imports OK with no error dialog or python error message): IPython, sympy These packages throw a syntax error (due to the hyphen) but presumably are OK (maybe called by other packages where the syntax is OK?): Intel-openmp, mkl-service, numpy-base, python-dateutil These packages throw a module could not be found error but conda says they’re definitely installed and they appear in the site-packages, as specified: enum34: egg-info only futures: dist-info only mkl: mkl only (no egg-info or dist-info) mkl_fft: mkl_fft and egg-info (no dist-info) These packages throw a module could not be found error but conda says they’re definitely installed so presumably they’re in a compiled version only, inside another package (they have no package of their own in site-packages): blas, freetype, hdf5, icc_rt, icu, jpeg, libpng, pyqt, qt These packages throw a MSVC++ runtime error R6034 dialog and a python DLL initialization routine failed error, and the error location is as specified: fastcache: line 27, in <module> from ._lrucache import clru_cache h5py: line 26, in <module> from . import _errors kiwisolver: File "<console>", line 1, in <module> yt: (2 MSVC++ runtime error dialogs then) python line 21, in <module> from yt.utilities.lib.fnv_hash import fnv_hash Hopefully, these results might help someone much more knowledgeable than me to tease out where the problem is occurring.