title: Fail to load libraries after upgrading R to 3.6.0 on Mac
body: <p>I needed to install the R package <code>quadprog</code>, which only works for R with version 3.6.0. So I installed R (<code>3.6.0</code> version), and open it with <code>RStudio</code>. But now I <strong>failed</strong> to load any libraries, even after I installed the packages <strong>successfully</strong> using <code>install.packages("package_name")</code>. Specifically, the libraries I need to load are <code>caret</code>, <code>forecast</code> and <code>ggplot2</code>. I tried re-installing <strong>R</strong> but it still does not work. The error message I get is</p>
  
  <blockquote>
    <p>Error: package or namespace load failed for ‘forecast’ in
    dyn.load(file, DLLpath = DLLpath, ...):  unable to load shared object
    '/Library/Frameworks/R.framework/Versions/3.6/Resources/library/Rcpp/libs/Rcpp.so':
    dlopen(/Library/Frameworks/R.framework/Versions/3.6/Resources/library/Rcpp/libs/Rcpp.so,
    6): Symbol not found: ___cxa_uncaught_exceptions   Referenced from:
    /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libc++.1.dylib
    Expected in: /usr/lib/libc++abi.dylib  in
    /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libc++.1.dylib</p>
  </blockquote>
  
  <p>After installing <code>Rcpp</code> package successfully with <code>install.packages("Rcpp")</code> , I still got the message above when I tried <code>library(Rcpp)</code>. So I am completely stumbled here...(before upgrades, everything works fine except I cannot install <code>quadprog</code>, so cannot install <code>forecast</code> package as well). Can anyone please help me fix this issue?</p>
  
  <p>Please see below the images showing that the packages are stored in the same directory path of the <code>R.</code></p>
  
  <p><a href="https://i.stack.imgur.com/w2svr.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/w2svr.png" alt="enter image description here"></a></p>
  
  <p><a href="https://i.stack.imgur.com/o4Z3b.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/o4Z3b.png" alt="enter image description here"></a></p>