Every so often something I do at the REPL in Allegro (6.2 on GNU/Linux) will confuse SLIME. I'll see this message in the minibuffer and will get no response.

error in process filter: No frame at point

If I hit return a couple times I get:

; No value

and the prompt back. Here's an elisp backtrace:

Debugger entered--Lisp error: (error "No frame at point") signal(error ("No frame at point")) error("No frame at point") (cond (frame (car frame)) (t (error "No frame at point"))) (let ((frame ...)) (cond (frame ...) (t ...))) sldb-frame-number-at-point() (save-excursion (sldb-backward-frame) (sldb-frame-number-at-point)) sldb-previous-frame-number() (let ((number ...)) (cond (...) (t ...))) (save-excursion (mapc (function sldb-insert-frame) frames) (let (...) (cond ... ...))) (if (null frames) nil (when maximum-length (assert ...)) (save-excursion (mapc ... frames) (let ... ...))) (unless (null frames) (when maximum-length (assert ...)) (save-excursion (mapc ... frames) (let ... ...))) sldb-insert-frames(((0 #("(SWANK::DEBUG-IN-EMACS #<READER-ERROR @ #x717506aa>)" 0 52 ...) (:location ... ... nil)) (1 #("((FLET SWANK:SWANK-DEBUGGER-HOOK SWANK::DEBUG-IT))" 0 50 ...) (:location ... ... nil)) (2 #("(SWANK:SWANK-DEBUGGER-HOOK #<READER-ERROR @ #x717506aa> #<Function SWANK-DEBUGGER-HOOK>)" 0 88 ...) (:location ... ... nil)) (3 #("(ERROR READER-ERROR :STREAM #<STRING-INPUT-SIMPLE-STREAM "(tpl:processes)" pos 14 @ #x7174fa4a> :FORMAT-CONTROL "~?~@[ [file position = ~d]~]" :FORMAT-ARGUMENTS ("~\nThe symbol ~s is not external in the ~a package." ("PROCESSES" "TOP-LEVEL") 14))" 0 245 ...) (:error "Unknown source location for ERROR")) (4 #("(READ #1=#<STRING-INPUT-SIMPLE-STREAM "(tpl:processes)" pos 14 @ #x7174fa4a> NIL #1#)" 0 85 ...) (:error "Unknown source location for READ")) (5 #("(SWANK::EVAL-REGION "(tpl:processes)\n" T)" 0 41 ...) (:location ... ... nil)) (6 #("((:INTERNAL SWANK:LISTENER-EVAL 0))" 0 35 ...) (:location ... ... nil)) (7 #("((METHOD SWANK-BACKEND:CALL-WITH-SYNTAX-HOOKS (T)) #<Closure (:INTERNAL SWANK:LISTENER-EVAL 0) @ #x71750632>)" 0 109 ...) (:location ... ... nil)) (8 #("(SWANK:LISTENER-EVAL "(tpl:processes)\n")" 0 40 ...) (:location ... ... nil)) (9 #("(EVAL (SWANK:LISTENER-EVAL "(tpl:processes)\n"))" 0 47 ...) (:error "Unknown source location for EVAL")) (10 #("(SWANK::EVAL-FOR-EMACS (SWANK:LISTENER-EVAL "(tpl:processes)\n") "CL-USER" 130)" 0 78 ...) (:location ... ... nil)) (11 #("(FUNCALL SWANK::EVAL-FOR-EMACS (SWANK:LISTENER-EVAL "(tpl:processes)\n") "CL-USER" 130)" 0 86 ...) (:error "Unknown source location for FUNCALL")) (12 #("(SWANK::READ-FROM-EMACS)" 0 24 ...) (:location ... ... nil)) (13 #("(SWANK::SLDB-LOOP 6)" 0 20 ...) (:location ... ... nil)) (14 #("((:INTERNAL SWANK::DEBUG-IN-EMACS 0))" 0 37 ...) (:location ... ... nil)) (15 #("((METHOD SWANK-BACKEND:CALL-WITH-DEBUGGING-ENVIRONMENT (T)) #<Function (:INTERNAL SWANK::DEBUG-IN-EMACS 0)>)" 0 108 ...) (:location ... ... nil)) (16 #("(SWANK::DEBUG-IN-EMACS #<READER-ERROR @ #x7183d94a>)" 0 52 ...) (:location ... ... nil)) (17 #("((FLET SWANK:SWANK-DEBUGGER-HOOK SWANK::DEBUG-IT))" 0 50 ...) (:location ... ... nil)) (18 #("(SWANK:SWANK-DEBUGGER-HOOK #<READER-ERROR @ #x7183d94a> #<Function SWANK-DEBUGGER-HOOK>)" 0 88 ...) (:location ... ... nil)) (19 #("(ERROR READER-ERROR :STREAM #<STRING-INPUT-SIMPLE-STREAM "(tpl:processes)" pos 14 @ #x7183d932> :FORMAT-CONTROL "~?~@[ [file position = ~d]~]" :FORMAT-ARGUMENTS ("~\nThe symbol ~s is not external in the ~a package." ("PROCESSES" "TOP-LEVEL") 14))" 0 245 ...) (:error "Unknown source location for ERROR"))) nil) (if (equal sldb-level level) nil (setq buffer-read-only nil) (sldb-mode) (unless sldb-saved-window-configuration (setq sldb-saved-window-configuration ...)) (setq slime-current-thread thread) (setq sldb-level level) (setq mode-name (format "sldb[%d]" sldb-level)) (setq sldb-condition condition) (setq sldb-restarts restarts) (sldb-insert-condition condition) (insert (in-sldb-face section #("Restarts:" 0 9 ...)) "\n") (sldb-insert-restarts restarts) (insert "\n" (in-sldb-face section #("Backtrace:" 0 10 ...)) "\n") (setq sldb-backtrace-start-marker (point-marker)) (sldb-insert-frames (sldb-prune-initial-frames frames) nil) (run-hooks (quote sldb-hook)) (pop-to-buffer (current-buffer)) (setq buffer-read-only t) (when (and slime-stack-eval-tags ...) (recursive-edit))) (unless (equal sldb-level level) (setq buffer-read-only nil) (sldb-mode) (unless sldb-saved-window-configuration (setq sldb-saved-window-configuration ...)) (setq slime-current-thread thread) (setq sldb-level level) (setq mode-name (format "sldb[%d]" sldb-level)) (setq sldb-condition condition) (setq sldb-restarts restarts) (sldb-insert-condition condition) (insert (in-sldb-face section #("Restarts:" 0 9 ...)) "\n") (sldb-insert-restarts restarts) (insert "\n" (in-sldb-face section #("Backtrace:" 0 10 ...)) "\n") (setq sldb-backtrace-start-marker (point-marker)) (sldb-insert-frames (sldb-prune-initial-frames frames) nil) (run-hooks (quote sldb-hook)) (pop-to-buffer (current-buffer)) (setq buffer-read-only t) (when (and slime-stack-eval-tags ...) (recursive-edit))) (save-current-buffer (set-buffer (sldb-get-buffer thread)) (unless (equal sldb-level level) (setq buffer-read-only nil) (sldb-mode) (unless sldb-saved-window-configuration ...) (setq slime-current-thread thread) (setq sldb-level level) (setq mode-name ...) (setq sldb-condition condition) (setq sldb-restarts restarts) (sldb-insert-condition condition) (insert ... "\n") (sldb-insert-restarts restarts) (insert "\n" ... "\n") (setq sldb-backtrace-start-marker ...) (sldb-insert-frames ... nil) (run-hooks ...) (pop-to-buffer ...) (setq buffer-read-only t) (when ... ...))) (with-current-buffer (sldb-get-buffer thread) (unless (equal sldb-level level) (setq buffer-read-only nil) (sldb-mode) (unless sldb-saved-window-configuration ...) (setq slime-current-thread thread) (setq sldb-level level) (setq mode-name ...) (setq sldb-condition condition) (setq sldb-restarts restarts) (sldb-insert-condition condition) (insert ... "\n") (sldb-insert-restarts restarts) (insert "\n" ... "\n") (setq sldb-backtrace-start-marker ...) (sldb-insert-frames ... nil) (run-hooks ...) (pop-to-buffer ...) (setq buffer-read-only t) (when ... ...))) sldb-setup(1 7 (#("The symbol "PROCESSES" is not external in the TOP-LEVEL package. [file\nposition = 14]" 0 85 (face sldb-topline-face)) #(" [Condition of type READER-ERROR]" 0 35 (face sldb-condition-face)) nil) ((#("RETURN-VALUE" 0 12 ...) #("Return a value instead of calling PROCESSES." 0 44 ...)) (#("USE-VALUE" 0 9 ...) #("Try calling a function other than PROCESSES." 0 44 ...)) (#("STORE-VALUE" 0 11 ...) #("Setf the symbol-function of PROCESSES and call it again." 0 56 ...)) (#("ABORT" 0 5 ...) #("Abort handling SLIME request." 0 29 ...)) (#("ABORT" 0 5 ...) #("Abort entirely from this process." 0 33 ...))) ((0 #("(SWANK::DEBUG-IN-EMACS #<READER-ERROR @ #x717506aa>)" 0 52 ...) (:location ... ... nil)) (1 #("((FLET SWANK:SWANK-DEBUGGER-HOOK SWANK::DEBUG-IT))" 0 50 ...) (:location ... ... nil)) (2 #("(SWANK:SWANK-DEBUGGER-HOOK #<READER-ERROR @ #x717506aa> #<Function SWANK-DEBUGGER-HOOK>)" 0 88 ...) (:location ... ... nil)) (3 #("(ERROR READER-ERROR :STREAM #<STRING-INPUT-SIMPLE-STREAM "(tpl:processes)" pos 14 @ #x7174fa4a> :FORMAT-CONTROL "~?~@[ [file position = ~d]~]" :FORMAT-ARGUMENTS ("~\nThe symbol ~s is not external in the ~a package." ("PROCESSES" "TOP-LEVEL") 14))" 0 245 ...) (:error "Unknown source location for ERROR")) (4 #("(READ #1=#<STRING-INPUT-SIMPLE-STREAM "(tpl:processes)" pos 14 @ #x7174fa4a> NIL #1#)" 0 85 ...) (:error "Unknown source location for READ")) (5 #("(SWANK::EVAL-REGION "(tpl:processes)\n" T)" 0 41 ...) (:location ... ... nil)) (6 #("((:INTERNAL SWANK:LISTENER-EVAL 0))" 0 35 ...) (:location ... ... nil)) (7 #("((METHOD SWANK-BACKEND:CALL-WITH-SYNTAX-HOOKS (T)) #<Closure (:INTERNAL SWANK:LISTENER-EVAL 0) @ #x71750632>)" 0 109 ...) (:location ... ... nil)) (8 #("(SWANK:LISTENER-EVAL "(tpl:processes)\n")" 0 40 ...) (:location ... ... nil)) (9 #("(EVAL (SWANK:LISTENER-EVAL "(tpl:processes)\n"))" 0 47 ...) (:error "Unknown source location for EVAL")) (10 #("(SWANK::EVAL-FOR-EMACS (SWANK:LISTENER-EVAL "(tpl:processes)\n") "CL-USER" 130)" 0 78 ...) (:location ... ... nil)) (11 #("(FUNCALL SWANK::EVAL-FOR-EMACS (SWANK:LISTENER-EVAL "(tpl:processes)\n") "CL-USER" 130)" 0 86 ...) (:error "Unknown source location for FUNCALL")) (12 #("(SWANK::READ-FROM-EMACS)" 0 24 ...) (:location ... ... nil)) (13 #("(SWANK::SLDB-LOOP 6)" 0 20 ...) (:location ... ... nil)) (14 #("((:INTERNAL SWANK::DEBUG-IN-EMACS 0))" 0 37 ...) (:location ... ... nil)) (15 #("((METHOD SWANK-BACKEND:CALL-WITH-DEBUGGING-ENVIRONMENT (T)) #<Function (:INTERNAL SWANK::DEBUG-IN-EMACS 0)>)" 0 108 ...) (:location ... ... nil)) (16 #("(SWANK::DEBUG-IN-EMACS #<READER-ERROR @ #x7183d94a>)" 0 52 ...) (:location ... ... nil)) (17 #("((FLET SWANK:SWANK-DEBUGGER-HOOK SWANK::DEBUG-IT))" 0 50 ...) (:location ... ... nil)) (18 #("(SWANK:SWANK-DEBUGGER-HOOK #<READER-ERROR @ #x7183d94a> #<Function SWANK-DEBUGGER-HOOK>)" 0 88 ...) (:location ... ... nil)) (19 #("(ERROR READER-ERROR :STREAM #<STRING-INPUT-SIMPLE-STREAM "(tpl:processes)" pos 14 @ #x7183d932> :FORMAT-CONTROL "~?~@[ [file position = ~d]~]" :FORMAT-ARGUMENTS ("~\nThe symbol ~s is not external in the ~a package." ("PROCESSES" "TOP-LEVEL") 14))" 0 245 ...) (:error "Unknown source location for ERROR")))) slime-dispatch-event((:debug 1 7 (#("The symbol "PROCESSES" is not external in the TOP-LEVEL package. [file\nposition = 14]" 0 85 ...) #(" [Condition of type READER-ERROR]" 0 35 ...) nil) ((#("RETURN-VALUE" 0 12 ...) #("Return a value instead of calling PROCESSES." 0 44 ...)) (#("USE-VALUE" 0 9 ...) #("Try calling a function other than PROCESSES." 0 44 ...)) (#("STORE-VALUE" 0 11 ...) #("Setf the symbol-function of PROCESSES and call it again." 0 56 ...)) (#("ABORT" 0 5 ...) #("Abort handling SLIME request." 0 29 ...)) (#("ABORT" 0 5 ...) #("Abort entirely from this process." 0 33 ...))) ((0 #("(SWANK::DEBUG-IN-EMACS #<READER-ERROR @ #x717506aa>)" 0 52 ...) ...) (1 #("((FLET SWANK:SWANK-DEBUGGER-HOOK SWANK::DEBUG-IT))" 0 50 ...) ...) (2 #("(SWANK:SWANK-DEBUGGER-HOOK #<READER-ERROR @ #x717506aa> #<Function SWANK-DEBUGGER-HOOK>)" 0 88 ...) ...) (3 #("(ERROR READER-ERROR :STREAM #<STRING-INPUT-SIMPLE-STREAM "(tpl:processes)" pos 14 @ #x7174fa4a> :FORMAT-CONTROL "~?~@[ [file position = ~d]~]" :FORMAT-ARGUMENTS ("~\nThe symbol ~s is not external in the ~a package." ("PROCESSES" "TOP-LEVEL") 14))" 0 245 ...) ...) (4 #("(READ #1=#<STRING-INPUT-SIMPLE-STREAM "(tpl:processes)" pos 14 @ #x7174fa4a> NIL #1#)" 0 85 ...) ...) (5 #("(SWANK::EVAL-REGION "(tpl:processes)\n" T)" 0 41 ...) ...) (6 #("((:INTERNAL SWANK:LISTENER-EVAL 0))" 0 35 ...) ...) (7 #("((METHOD SWANK-BACKEND:CALL-WITH-SYNTAX-HOOKS (T)) #<Closure (:INTERNAL SWANK:LISTENER-EVAL 0) @ #x71750632>)" 0 109 ...) ...) (8 #("(SWANK:LISTENER-EVAL "(tpl:processes)\n")" 0 40 ...) ...) (9 #("(EVAL (SWANK:LISTENER-EVAL "(tpl:processes)\n"))" 0 47 ...) ...) (10 #("(SWANK::EVAL-FOR-EMACS (SWANK:LISTENER-EVAL "(tpl:processes)\n") "CL-USER" 130)" 0 78 ...) ...) (11 #("(FUNCALL SWANK::EVAL-FOR-EMACS (SWANK:LISTENER-EVAL "(tpl:processes)\n") "CL-USER" 130)" 0 86 ...) ...) (12 #("(SWANK::READ-FROM-EMACS)" 0 24 ...) ...) (13 #("(SWANK::SLDB-LOOP 6)" 0 20 ...) ...) (14 #("((:INTERNAL SWANK::DEBUG-IN-EMACS 0))" 0 37 ...) ...) (15 #("((METHOD SWANK-BACKEND:CALL-WITH-DEBUGGING-ENVIRONMENT (T)) #<Function (:INTERNAL SWANK::DEBUG-IN-EMACS 0)>)" 0 108 ...) ...) (16 #("(SWANK::DEBUG-IN-EMACS #<READER-ERROR @ #x7183d94a>)" 0 52 ...) ...) (17 #("((FLET SWANK:SWANK-DEBUGGER-HOOK SWANK::DEBUG-IT))" 0 50 ...) ...) (18 #("(SWANK:SWANK-DEBUGGER-HOOK #<READER-ERROR @ #x7183d94a> #<Function SWANK-DEBUGGER-HOOK>)" 0 88 ...) ...) (19 #("(ERROR READER-ERROR :STREAM #<STRING-INPUT-SIMPLE-STREAM "(tpl:processes)" pos 14 @ #x7183d932> :FORMAT-CONTROL "~?~@[ [file position = ~d]~]" :FORMAT-ARGUMENTS ("~\nThe symbol ~s is not external in the ~a package." ("PROCESSES" "TOP-LEVEL") 14))" 0 245 ...) ...))) #<process SLIME Lisp>) slime-process-available-input() slime-net-filter(#<process SLIME Lisp> " (17 "((FLET SWANK:SWANK-DEBUGGER-HOOK SWANK::DEBUG-IT))" (:location (:file "/home/peter/cvs/slime/swank.lisp") (:position 39988) nil)) (18 "(SWANK:SWANK-DEBUGGER-HOOK #<READER-ERROR @ #x7183d94a> #<Function SWANK-DEBUGGER-HOOK>)" (:location (:file "/home/peter/cvs/slime/swank.lisp") (:position 39988) nil)) (19 "(ERROR READER-ERROR :STREAM #<STRING-INPUT-SIMPLE-STREAM \"(tpl:processes)\" pos 14 @ #x7183d932> :FORMAT-CONTROL \"~?~@[ [file position = ~d]~]\" :FORMAT-ARGUMENTS (\"~\nThe symbol ~s is not external in the ~a package.\" (\"PROCESSES\" \"TOP-LEVEL\") 14))" (:error "Unknown source location for ERROR"))))\n..(:debug-activate 1 7)\n")

-Peter