Cannot install devtools package on mac - r

Question

I would like to use the ggbiplot function in R. I tried to install the devtools package first, but it doesn´t work.
I am using R studio Version 1.2.1335 and have a mac with version 10.14.5
Tried different types of code
install.packages("devtools")
library(devtools)
install_github("vqv/ggbiplot")
library(ggbiplot)
or
library(devtools)
install_github("ggbiplot", "vqv")
and i tried to answer this questiion Do you want to install from sources the packages which need compilation?
y/n: with y and n
install.packages("devtools")
also installing the dependencies ‘fs’, ‘usethis’, ‘testthat’
There are binary versions available but the source versions are later:
binary source needs_compilation
fs 1.2.7 1.3.1 TRUE
usethis 1.4.0 1.5.1 FALSE
testthat 2.0.1 2.2.1 TRUE
devtools 1.13.6 2.1.0 FALSE
Do you want to install from sources the packages which need compilation?
y/n: n
versuche URL 'https://cran.rstudio.com/bin/macosx/el-capitan/contrib/3.4/fs_1.2.7.tgz'
Content type 'application/x-gzip' length 746131 bytes (728 KB)
downloaded 728 KB
versuche URL 'https://cran.rstudio.com/bin/macosx/el-capitan/contrib/3.4/testthat_2.0.1.tgz'
Content type 'application/x-gzip' length 1660043 bytes (1.6 MB)
downloaded 1.6 MB
The downloaded binary packages are in
/var/folders/c0/sg0bg4dx2vz4qw6zdqgc4fpr0000gn/T//RtmpaTVVAF/downloaded_packages
installing the source packages ‘usethis’, ‘devtools’
versuche URL 'https://cran.rstudio.com/src/contrib/usethis_1.5.1.tar.gz'
Content type 'application/x-gzip' length 620225 bytes (605 KB)
downloaded 605 KB
versuche URL 'https://cran.rstudio.com/src/contrib/devtools_2.1.0.tar.gz'
Content type 'application/x-gzip' length 378899 bytes (370 KB)
downloaded 370 KB
installing source package ‘usethis’ ...
** Paket ‘usethis’ erfolgreich entpackt und MD5 Summen überprüft
** R
** inst
** preparing package for lazy loading
Error in loadNamespace(i, c(lib.loc, .libPaths()), versionCheck = vI[[i]]) :
namespace ‘fs’ 1.2.7 is being loaded, but >= 1.3.0 is required
ERROR: lazy loading failed for package ‘usethis’
removing ‘/Library/Frameworks/R.framework/Versions/3.4/Resources/library/usethis’
Warning in install.packages :
installation of package ‘usethis’ had non-zero exit status
ERROR: dependency ‘usethis’ is not available for package ‘devtools’
removing ‘/Library/Frameworks/R.framework/Versions/3.4/Resources/library/devtools’
Warning in install.packages :
installation of package ‘devtools’ had non-zero exit status
The downloaded source packages are in
‘/private/var/folders/c0/sg0bg4dx2vz4qw6zdqgc4fpr0000gn/T/RtmpaTVVAF/downloaded_packages’
library(devtools)
there is no package called ‘devtools’

Answer 1

I had the same issue (macOS Catalina 10.15.3, R version 3.6.2) and solved it by first installing 'openssl#1.1'
If you have homebrew you can install this via the command line
'brew install openssl#1.1'
(you also need Xcode and command line tools installed!)