If you just want to fix the issue quickly, scroll down to the "solution" section below.

If you're a Homebrew user and you installed node via Homebrew, there is a major philosophical issue with the way Homebrew and NPM work together. If you install node with Homebrew and then try to do npm update npm -g, you may see an error like this:

$ npm update npm -g

First time using md. It is awesome! MarkDown tutorial

Solution: Check the following items on your server/computer and your project folder:

• PHP Module mod_rewrite. Check it in httpd.conf under the directory of your apache install. In some cases there will be a comment ("#") before those two lines of code. To make it work, just uncomment in httpd.conf