Dear Stephane and Eberhard, As an addendum to my previous response, I uninstalled the Rcmdr package and all of its direct and indirect dependencies and then reinstalled the package -- on a macOS 11.1 system running R 4.0.3 with all other packages up-to-date. I then reinstalled the Rcmdr and dependencies via the command install.packages("Rcmdr"), and responded "no" when asked whether to install some packages from source (perhaps this is the explanation for the problem, if your students responded "yes" without having Xcode installed). Following these steps, everything (still) works fine. I therefore can't duplicate your students' problem, which makes it hard to suggest how to fix it, without having some additional details. Best, John On 2021-01-11 3:33 p.m., John Fox wrote:> Dear Stephane and Eberhard, > > It should not be necessary to install Xcode (which includes otools) to > install and use the Rcmdr package on macOS because it shouldn't be > necessary to install the CRAN packages required from source. I'm > currently running the Rcmdr on two macOS 11.1 systems, with all CRAN > packages up-to-date, and don't have any problems. > > Stephane, have you and your students checked the Rcmdr installation > notes (at > <https://socialsciences.mcmaster.ca/jfox/Misc/Rcmdr/installation-notes.html>) > and followed the instructions there? If you have, and still experience > this problem, it would help to have some more information about what > they did to install the Rcmdr and what happened. > > In the meantime, I'll try a fresh install of the Rcmdr and dependencies > to see whether I encounter any difficulties. > > Best, > ?John >