I suspect the double quotes are part of file names, hence files cannot be found. Perhaps try remove them in macro argument. Hope this helps De : Rudolf Bahr Envoyé le :lundi 14 octobre 2019 18:50 À : ntg-context@ntg.nl Objet :[NTG-context] \ctxlua and \startluacode ... \stopluacode Dear List! THis MWE must be faulty, but where is the error? ==================================================== \startluacode userdata = userdata or {} function userdata.file_exists (name) local name = name local f = assert ( io.open ( name, "r" )) if f then f:close () context ( name ) context ( " exists!" ) else context ( name ) context ( " doesn't exist!" ) end end \stopluacode \starttext \def\lookupfile#1% {\ctxlua{userdata.file_exists([==[#1]==])}} \lookupfile{"$HOME/context-tests/AAA.lua"} % "AAA.lua" intentionally does exist \lookupfile{"$HOME/context-tests/BBB.lua"} % "BBB.lua" intentionally doesn't exist \stoptext ==================================================== It makes no difference in commenting out the first or the second "\lookupfile" command. The error message eventually is always nearly the same: token call, execute: [ctxlua]:8: "$HOME/context-tests/AAA.lua": No such file or directory token call, execute: [ctxlua]:8: "$HOME/context-tests/BBB.lua": No such file or directory I'm using: LuaMetaTeX, Version 2.00.0 ConTeXt ver: 2019.10.10 18:15 MKIV beta fmt: 2019.10.12 int: english/english Please, any ideas? Regards, Rudolf ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________