title: node js Error while installing npm install express code UNABLE_TO_VERIFY_LEAF_SIGNATURE unable to verify the first certificate
body: <p>I have installed nodejs version node-v4.5.0-x64.msi</p>
  
  <p>I am installing express using  <strong>npm install express</strong> in windows but getting following error </p>
  
  <pre><code>npm WARN package.json demo2@1.0.0 No description                                    
  npm WARN package.json demo2@1.0.0 No repository field.
  
  npm WARN package.json demo2@1.0.0 No README data
  npm ERR! Windows_NT 6.3.9600
  npm ERR! argv "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\
  node_modules\\npm\\bin\\npm-cli.js" "install" "express"
  npm ERR! node v4.5.0
  npm ERR! npm  v2.15.9
  npm ERR! code UNABLE_TO_VERIFY_LEAF_SIGNATURE
  
  npm ERR! unable to verify the first certificate
  npm ERR!
  npm ERR! If you need help, you may report this error at:
  npm ERR!     &lt;https://github.com/npm/npm/issues&gt;
  
  npm ERR! Please include the following file with any support request:
  npm ERR!     D:\user\Node\demo2\npm-debug.log
  </code></pre>
  
  <p><strong>Update</strong>
  not only express package I was not able to install any package </p>