Moving from 2.5 to 3.0
Be sure to read the guide on moving from 2.5 to 3.0 if you are planning to convert an existing project to the all-new 3.0.0. It tells you how to deal with licenses, migrating data, dealing with version control and more. It also tells you about important differences between 3.0 and 2.5 that you have to be aware of. In short, read it!