SQLServer Upgrade Advisor 2014 hanging
As far as I know there is issue with SQL Server 2014 upgrade advisor, it sometime hangs when analyzing the workload for migration. What you can do is download SQL Server 2016 upgrade advisor which is now called as Data Migration Assistant V 3.1. As per Microsoft the upgrade advisor 2016 is deprecated and is replaced by Data migration assistant. 

I am not quite sure but I believe MS folks knew about this that is why they moved to much better tool data migration assistant.

This does not comes inbuild with SQL Server installation media it is a separate download.