sbt fails with java.lang.NoClassDefFoundError: sbt/ConsoleOut$

the only thing I remember doing was installing the new intellij (v13). Is this related?

It could be related.

Try:

rm -rf ~/.ivy/cache
mv ~/.sbt ~/.sbt.old

In sbt:

clean

Results in re-resolution of ivy artifacts on next compile, without having to clear the ivy cache.

If the ivy itself is the problem then above solution is a good fallback.

Most probably this issue comes from the IntelliJ IDE, Close all the running processes of the IDE and start it again.