With everything being new, what version of Python is Bro running as? I usually change the python declaration in bro/bin/bro,/bro/bin/broctl, and /bro/share/broctl/scripts/stats-2-csv to python2 because they begin with python and the python wrapper will try send it to the system wide python level which may be a python3 version and you will have problems.

Hope that helps!