title: not able to install anything because of brew no such file or directory error
body: <p>I am trying to install do <code>brew install python3</code> on my mac but i keep getting the following errors:  </p>
  
  <p>this is the first error: </p>
  
  <blockquote>
    <p>No such file or directory @ dir_chdir - /usr/local/Cellar</p>
  </blockquote>
  
  <p>then a bit later i get this error: </p>
  
  <blockquote>
    <p>An exception occurred within a child process:
      Errno::EPERM: Operation not permitted @ dir_s_mkdir - /usr/local/Cellar</p>
  </blockquote>
  
  <p>I have ran <code>brew update</code> then <code>brew doctor</code> the <code>brew cleanup</code> but keep getting the error.<br>
  I have also checked to see if xcode is up-to-date but according to the appstore all my apps are up-to-date. </p>
  
  <p>How do i fix this problem?</p>
  
  <p><strong>PS</strong> i also get these errors when trying to install other packages from brew. </p>