Please note in order to upgrade you need to cover the requirements mentioned here
. You will have to upgrade your sites to 3.7. Refer to the video and the documentation in the link provided so you can see which files you will need in order to get the projects upgraded successfully.
All the best,
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items