Hi, I am new to yt and enzo. I have been able to compile and run a few 'test' simulations in enzo. However, when I use 'yt plot xxx', it complains the following: 310 if active_particles: 311 ptypes = _next_token_line("PresentParticleTypes", f)--> 312 counts = [int(c) for c in _next_token_line("ParticleTypeCounts", f)] 313 for ptype in self.parameters.get("AppendActiveParticleType", []): 314 if ptype in ptypes: TypeError: 'NoneType' object is not iterable ------ I recall it worked when I was using yt 2.x version a few months ago. The problem seems to appear for the current yt. The tests with enzo I ran were MHDCTOrszangTang in 2D, ShearingBox in 3D (there are no particles). Any clues? Cheers, Kit