Hi @jingliu ,
it looks like there is a hook that is executed when starting ROOT in a notebook that tries to load and use ROOT7 graphics. The maintainers of the Fedora ROOT package split ROOT into several sub-packages, so my guess is that you don’t have a necessary ROOT sub-package install (the one that provides ROOT::Experimental::RCanvas::GetCanvases()).
Given the list here: root - Fedora Packages my guess is that you need root-graf-gpadv7 . You could/should report to the maintainers of the Fedora packages that this dependency is missing.
Cheers,
Enrico