Hi Tsz Ka,
line 219, in _run_halo_finder_add_to_db
self.period = self.pf.domain_right_edge -
AttributeError: 'MergerTree' object has no attribute 'pf'
Sorry for the error! I just made a simple fix, and if you update your yt install, it should work now (or fail for an entirely different reason!). Let us know if you have more problems.
Stephen Skory email@example.com http://stephenskory.com/ 510.621.3687 (google voice)