I ran into a problem today where my Slime connection would suddenly drop if I loaded a file that contained UTF characters.

Luckily the #lisp bods saved the day, here’s how you fix it:

1. Add (setq slime-net-coding-system ‘utf-8-unix) to your .emacs
2. Add the :coding-system “utf-8-unix” keyword parameter to your (swank:create-server) call

There’s more information available here.

Cheers, Dave.