I keep getting this error, regardless of which root version I try:
File "/cvmfs/sft.cern.ch/lcg/releases/LCG_98python3_ATLAS_1/ROOT/v6.22.00/x86_64-centos7-gcc8-opt/lib/ROOT/_facade.py", line 163, in _fallback_getattr
raise AttributeError("Failed to get attribute {} from ROOT".format(name))
AttributeError: Failed to get attribute Double from ROOT
As it seems connected to python @etejedor may help you. It would be helpful if you could provide a small reproducer and also tell us on which platform you are running. It looks like you are using ROOT version 6.22