I frequently see this (see debugger backtrace below) when starting SLIME. Not all the time. I suspect it's a timing issue. Anyone see this? Anyone looked into fixing? Thanks, --Mark Undefined function SWANK::SYMBOL-INDENTATION called with arguments (:BREAK-OPTIONS-STRING) . [Condition of type CCL::UNDEFINED-FUNCTION-CALL] Restarts: 0: [CONTINUE] Retry applying SWANK::SYMBOL-INDENTATION to (:BREAK-OPTIONS-STRING). 1: [USE-VALUE] Apply specified function to (:BREAK-OPTIONS-STRING) this time. 2: [STORE-VALUE] Specify a function to use as the definition of SWANK::SYMBOL-INDENTATION. 3: [ABORT-BREAK] Reset this thread 4: [ABORT] Kill this thread Backtrace: 0: ((:INTERNAL SWANK::CONSIDER SWANK::UPDATE-INDENTATION/DELTA-FOR-EMACS) :BREAK-OPTIONS-STRING) 1: (#<Anonymous Function #x302000BD1E4F> :BREAK-OPTIONS-STRING) 2: (CCL::APPLY-TO-HTAB-SYMS #<COMPILED-LEXICAL-CLOSURE #x2389553F> #(:NFRAMES #<Unbound> :CODE 0 :PAUSE-PERIOD 0 ...)) 3: (CCL::ITERATE-OVER-PRESENT-SYMBOLS #<Package "KEYWORD"> #<COMPILED-LEXICAL-CLOSURE #x2389553F>) 4: (CCL::ITERATE-OVER-ALL-SYMBOLS #<COMPILED-LEXICAL-CLOSURE #x2389553F>) 5: (SWANK::UPDATE-INDENTATION/DELTA-FOR-EMACS #<HASH-TABLE :TEST EQ size 228/305 #x302000AC574D> (#<Package "X86-DARWIN64"> #<Package "X8664"> #<Package "KEYWORD"> #<Package "CCL"> ..) #<Package "COMMON-.. 6: (SWANK::PERFORM-INDENTATION-UPDATE #<MULTITHREADED-CONNECTION #x302000AC56AD> (#<Package "X86-DARWIN64"> #<Package "X8664"> #<Package "KEYWORD"> #<Package "CCL"> #<Package "COMMON-LISP"> ..) #<Package.. 7: ((:INTERNAL SWANK::INDENTATION-CACHE-LOOP)) 8: (SWANK/BACKEND:CALL-WITH-DEBUGGER-HOOK #<Compiled-function SWANK:SWANK-DEBUGGER-HOOK #x302000A414FF> #<COMPILED-LEXICAL-CLOSURE (:INTERNAL SWANK::INDENTATION-CACHE-LOOP) #x302000ACFD1F>) 9: (SWANK::INDENTATION-CACHE-LOOP #<MULTITHREADED-CONNECTION #x302000AC56AD>) 10: (CCL::RUN-PROCESS-INITIAL-FORM #<PROCESS swank-indentation-cache-thread(6) [Active] #x302000AC982D> (#<COMPILED-LEXICAL-CLOSURE (:INTERNAL CCL::%PROCESS-RUN-FUNCTION) #x302000AC95BF>)) 11: ((:INTERNAL (CCL::%PROCESS-PRESET-INTERNAL (PROCESS))) #<PROCESS swank-indentation-cache-thread(6) [Active] #x302000AC982D> (#<COMPILED-LEXICAL-CLOSURE (:INTERNAL ..))) 12: ((:INTERNAL CCL::THREAD-MAKE-STARTUP-FUNCTION))