I am trying to get a project to open in 2017. It hangs on compiling scripts. (hold on… compiling scripts)
If I kill mono.exe via task manager it will go into unity then I can load the C# project in mono develop or visual studio and build it just fine.
But If I try to start it in the player then mono.exe starts running and hangs. .
Same problem here 
After converting from 5.6.3p1 → 2017.1 (or 2017.2) mono.exe hangs everytime i open the project
ScottAdams
did u solved the problem?
Yes I did @bromske. I forwarded my project to someone at Unity and they said it was hanging up in a large method in the C# script.
I refactored that method to be smaller and it now builds in 2017.