I'm tracking the head of both UCW and SLIME, with SBCL. SLIME recently added the external-format keyword to a bunch of different functions, including swank-backend:accept-connection. Accept-connection is used by UCW as its socket interface. It doesn't pass an encoding. Either UCW should pass an encoding, or accept-connection should pick up on the default *CODING-SYSTEM*, or swank-sbcl.lisp should pick up on it somewhere. The error I'm getting is in swank-sbcl.lisp, make-socket-io-stream. External-formal is nil, and thus falls through the ECASE. Right now, only swank:start-server, create-server, and create-swank-server pick up on the default coding system. The argument could be made that SLIME needs a sensible default in this situation. The argument could be made that UCW needs to be in control of this sort of thing. I'll leave it to you all. Chris Capel -- "What is it like to be a bat? What is it like to bat a bee? What is it like to be a bee being batted? What is it like to be a batted bee?" -- The Mind's I (Hofstadter, Dennet)