NOTE: This post is about the prior version of Ghost (0.x). In version 1.0 or later, the Ghost official team supports a tool to upgrade your app via
ghost command line tool.
Take the following steps, which is a short summary of the linked tutorial:
Download the latest Ghost and extract it
npm-shrinkwrap.json. Do NOT delete
content/. If you use custom settings on these files, make sure you backup them before deleting.
npm-shrinkwrap.json. If you modify any or all of these files and directories, you should modify it after copying it.
npm install --productionagain to install everything properly.