Re-run with -feature for details

In my case, I found the source of my error to the file /usr/local/etc/sbtopts. It had the following line added at the end by some program I had installed.

-Xms512M -Xmx1536M -Xss1M -XX:+CMSClassUnloadingEnabled XX:MaxPermSize=256M

Whenever sbt launches the above line is passed as arguments which was causing the above error. As these are java options to solve it either we can add -J before the above line or delete the line completely. This gets rid of -feature.

You have to add

scalacOptions += "-feature"

to your build.sbt and execute reload if your sbt console is running (or restart it).

Alternatively if you want to set it only for a single session, while in sbt console.

set scalacOptions += "-feature"

You can write, this setting is applied immediately, no need to reload or restart sbt console.

Just for completion if you're in the play/sbt repl you can modify the value of scalacOptions just for the session, like this: