Uncaught TypeError: Cannot read property ‘get_current’ of undefined

Client Object Model SP.ClientContext will not work if you are using minimal.master. If you are using minimal.master and want to use the client object model then you will need to add code that loads “sp.js” or you can just use v4.master.

Uncaught TypeError: Cannot read property 'get_current' of undefined
Chrome error
SP.ClientContext.get_current is null or not an object
IE error