I have MacOS Monterey 12.0.1, and installed ROOT via brew install root, which created a directory /opt/homebrew/Cellar/root/6.24.06/. I am now trying to read a .root file coming from MadGraph+Pythia8+Delphes. When I installed Delphes directly in MadGraph, it gave me examples of pyROOT commands to read these .root files. However all of these examples are failing for the same reason, related to the ExRootTreeReader (shown in photo):
(where Delphes_ROOT is a string of the location of my .root file). I was able to go through other PyROOT examples fine in the same Jupyter Notebook as in the photo (such as Exercise 1 of Steven Schramm’s PyROOT Tutorial). I tried googling the error “Failed to get attribute ExRootTreeReader from ROOT” but didn’t find a forum on this exact error.