velocyto is abandoned software with install problems. https://github.com/velocyto-team/velocyto.py/issues/414 Owners say "velocyto is now included in the STARSolo pipeline, which is both more flexible and quicker". So switch to STARSolo? - https://github.com/velocyto-team/velocyto.py/blob/master/README.md - https://github.com/alexdobin/STAR/tree/master