Why does sbt compile fail with StackOverflowError?

Question

I am working on a Scala project that has been in existence for a few years but is new to me. My task is to upgrade it from Scala 2.9.3 to 2.11.7, along with its dependencies. I

Answer 1

Add to the bottom of /usr/local/etc/sbtopts

-J-Xmx4G 
-J-Xss4M

All set.