Read the official Contao announcements.
TYPOlight 2.0 FINAL is available
by Leo Feyer
TYPOlight Open Source CMS 2.0 FINAL is available for download. If you are updating from a 2.0beta version, please run the update tool once (ignore the warning) and click on rename tables - and do not do anything else! Then proceed to the install tool. Take a look at the changelog to see what has been done.
Download this release from github.com.