This bug occurs in both guile version 3.0.4.38-64c894 and 3.0.4-1.2ubuntu3. I use Ubuntu 20.10. *** Steps to reproduce *** 1. Create file hello1.scm with the following contents: ---cut here--- (display "Hello world") (newline) ---cut here--- 2. Give command guild compile --to=tree-il -o hello1.tree-il hello1.scm 3. Give command guild compile --from=tree-il -o hello1.go hello1.tree-il *** Expected output *** File hello1.tree-il should be compiled to hello1.go *** Actual output *** ---cut here--- Backtrace: In /home/tohoyn/git/other/guile/meta/guild:     72:17 19 (main _) In srfi/srfi-1.scm:     634:9 18 (for-each # …) In scripts/compile.scm:    279:26 17 (_ _) In system/base/target.scm:      65:6 16 (with-target _ _) In system/base/compile.scm:     187:6 15 (compile-file "hello1.tree-il" #:output-file _ #:from _ …)      53:4 14 (call-with-output-file/atomic _ _ _) In ice-9/boot-9.scm:   1736:10 13 (with-exception-handler _ _ #:unwind? _ # _) In system/base/compile.scm:     69:11 12 (_)    190:11 11 (_ #)    335:18 10 (read-and-compile # #:from _ # …)      84:6  9 (compute-compiler _ #f 2 1 (#:to-file? #t #:warnings #)) In system/base/language.scm:     63:11  8 (lookup-language #f) In ice-9/threads.scm:     390:8  7 (_ _) In ice-9/boot-9.scm:   3223:13  6 (_)   3493:26  5 (try-module-autoload _ _)    222:29  4 (map1 (language #f))    222:17  3 (map1 (#f))   3494:48  2 (_ _) In unknown file:            1 (symbol->string #f) In ice-9/boot-9.scm:   1669:16  0 (raise-exception _ #:continuable? _) ice-9/boot-9.scm:1669:16: In procedure raise-exception: In procedure symbol->string: Wrong type argument in position 1 (expecting symbol): #f ---cut here---      - Tommi Höynälänmaa