Dear All, my document ends with the index \startbackmatter \chapter{Rejstřík jmenný} \start \switchtobodyfont[8pt] \placeindexname \stop \stopbackmatter \startbackmatter \chapter{Rejstřík věcný} \start \switchtobodyfont[8pt] \placeindexsubject \stop \stopbackmatter At the beginning there is a condition for one word (kind of manual column balancing) - but according to the log, see below, this seems to be an issue: \newconditional\IndexState \define[1]\IndexInternalCommand {\doifelse{#1}{Dolsko}{\global\settrue\IndexState}{\global\setfalse\IndexSta te}#1} \define[1]\IndexCommand {\setfalse\IndexState \setbox\scratchbox\hbox{#1}% \ifconditional\IndexState \column \fi \box\nextbox} \defineregister[indexname][indexnames] \setupregister[indexname][command=\Word, textcommand=\IndexCommand, deeptextcommand=\IndexInternalCommand] \defineregister[indexsubject][indexsubjects] \setupregister[indexsubject][command=\Word] \setupheadtext[indexname=Rejstřík jmenný] \setupheadtext[indexsubject=Rejstřík věcný] This worked in luatex 1.0.1, but in LMTX I am getting: structures > begin of sectionblock 'backpart' structure > sectioning > chapter @ level 2 : 0.1 -> Rejstřík jmenný fonts > defining > font 'palab', feature 'locl', script 'latn', no language 'dflt' tex error > tex error on line 25 in file D:/context-lmtx/tex/texmf-context/tex/context/base/mkiv/page-run.mkiv: ? <argument> [internal expandable lua function call] \IndexInternalCommand ...\setfalse \IndexState }#1 \IndexCommand ...ate \setbox \scratchbox \hbox {#1 }\ifconditional \IndexStat... \doapplyregisterentrycommand ...extcommand {#2}}}} \dostoptagged \registerentry ...plyregisterentrycommand {#2}{#5} \fi \else \let \currentreg... l.25 } ...l.11633 \stop 15 16 \registerctxluafile{page-run}{} 17 18 \unprotect 19 20 \unexpanded\gdef\showprint{\dotripleempty\page_layouts_show_print} 21 22 \gdef\page_layouts_show_print[#1][#2][#3]% only english 23 {\setbuffer[crap]% 24 \unprotect 25 >> \definepapersize[X][\c!width=4em, \c!height=6em] 26 \definepapersize[Y][\c!width=12em,\c!height=14em] 27 \setuppapersize[X,#1][Y,#2] 28 \setuplayout[#3] 29 \setuplayout[\v!page] 30 \framed 31 [\c!offset=\v!overlay,\c!strut=\v!no, 32 \c!width=\paperwidth,\c!height=\paperheight] 33 {\ss ABC\par DEF}% 34 \protect 35 \endbuffer When I've seen that 'crap' and weird page dimensions, I thought it is part of the April fool, like all that LMTX announcement. This issue is not urgent, I was just curious how different the output is. Thanks, Jan