title: NPM Error : Error: EROFS: read-only file system, mkdir '/npm'
body: <p>I created an index.js, index.html and package.json file and I wanted to add express. When I write 'npm install express' in the terminal, I'm getting the error below. So far, I tried 'sudo npm install -g express', deleting node and npm completely and re-install. I also went through other questions over here but none of them worked out for me. Whatever I write with npm I get the same error. (I'm using macOS)</p>
  
  <p>Do you have any suggestions? </p>
  
  <p>This is the error I am getting:</p>
  
  <pre><code>Error: EROFS: read-only file system, mkdir '/npm'
  
  TypeError: Cannot read property 'loaded' of undefined
  
      at exit (/usr/local/lib/node_modules/npm/lib/utils/error-handler.js:97:27)
  
      at errorHandler (/usr/local/lib/node_modules/npm/lib/utils/error-handler.js:216:3)
  
      at /usr/local/lib/node_modules/npm/bin/npm-cli.js:78:20
  
      at cb (/usr/local/lib/node_modules/npm/lib/npm.js:225:22)
  
      at /usr/local/lib/node_modules/npm/lib/npm.js:263:24
  
      at /usr/local/lib/node_modules/npm/lib/config/core.js:81:7
  
      at Array.forEach (&lt;anonymous&gt;)
  
      at /usr/local/lib/node_modules/npm/lib/config/core.js:80:13
  
      at f (/usr/local/lib/node_modules/npm/node_modules/once/once.js:25:25)
  
      at afterExtras (/usr/local/lib/node_modules/npm/lib/config/core.js:171:20)
  
  /usr/local/lib/node_modules/npm/lib/utils/error-handler.js:97
  
    var doExit = npm.config.loaded ? npm.config.get('_exit') : true
  
                            ^
  
  TypeError: Cannot read property 'loaded' of undefined
  
      at exit (/usr/local/lib/node_modules/npm/lib/utils/error-handler.js:97:27)
  
      at process.errorHandler (/usr/local/lib/node_modules/npm/lib/utils/error-handler.js:216:3)
  
      at process.emit (events.js:223:5)
  
      at process._fatalException (internal/process/execution.js:150:25)
  </code></pre>