I've been using Rstudio for a while and recently I have been failing to install any packages. I have tried reinstall Rstudio and it is the newest version now but still unable to install any R packages. It gives the same error message for every package i install, following are the examples of errors and warnings i got.
Warning in strptime(xx, f <- "%Y-%m-%d %H:%M:%OS", tz = tz) :
unknown timezone 'zone/tz/2019c.1.0/zoneinfo/America/Los_Angeles'
- installing source package ‘ps’ ...
** package ‘ps’ successfully unpacked and MD5 sums checked
** libs
xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
ERROR: compilation failed for package ‘ps’ - removing ‘/Library/Frameworks/R.framework/Versions/3.3/Resources/library/ps’
Warning in install.packages :
installation of package ‘ps’ had non-zero exit status
Warning in strptime(xx, f <- "%Y-%m-%d %H:%M:%OS", tz = tz) :
unknown timezone 'zone/tz/2019c.1.0/zoneinfo/America/Los_Angeles' - installing source package ‘farver’ ...
** package ‘farver’ successfully unpacked and MD5 sums checked
** libs
xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
ERROR: compilation failed for package ‘farver’ - removing ‘/Library/Frameworks/R.framework/Versions/3.3/Resources/library/farver’
Warning in install.packages :
installation of package ‘farver’ had non-zero exit status