When I process files using the latest standalone ConTeXt ver: 2019.04.29 08:52 MKIV beta fmt: LuaTeX, Version 1.10.0 (TeX Live 2019)), I now get the following error message: lua error > lua error on line 8 in file env_Brill-01.tex: ...eXt/tex/texmf-context/tex/context/base/mkiv/font-oup.lua:1317: bad argument #1 to 'concat' (table expected, got number) The error log is as follows: return { ["filename"]="env_Brill-01.tex", ["lastcontext"]="\ \\font_helpers_low_level_define ...nsize }{\\m_font_designsize }\\scaledfontmode \ \\relax \\ifcase \\scaledfont...\ \\font_fallbacks_clone_unique ...w_level_define {#1}\\v_font_identifier_basic \ \\csname \\v_font_identifier...\ l.8 }\ \ \\font_fallbacks_prepare #1->\\clf_fontcollectionprepare {#1}\ \ \\font_fallbacks_prepare_indeed ... \\lastrawfontcall \\font_fallbacks_prepare #1\ \\endgroup \ <inserted text> ...nt_fallbacks_prepare_indeed \\m_font_fallbacks \ \\fi \\fi \ ...\ l.215 \\setupbodyfont[mainface, 10pt]\ ", ["lastluaerror"]="...eXt/tex/texmf-context/tex/context/base/mkiv/font-oup.lua:1317: bad argument #1 to 'concat' (table expected, got number)", ["lasttexerror"]="?", ["linenumber"]=8, ["luaerrorline"]="1317", ["offset"]=10, } This files process as they should with earlier versions. I will try to produce an mwe if needed but hope that it is not. Alan