I thought to check if this is already a known issue before I enter a bug. I do not remember if I've seen this before now.
When adding an array inside a longtable, it compiles OK with lualatex and with make4ht when not using mathjax. When using mathjax mode, I get a error: ------------------ (/usr/local/texlive/2019/texmf-dist/tex/generic/tex4ht/html5.4ht)) (./foo1.aux) (/usr/local/texlive/2019/texmf-dist/tex/latex/lm/ot1lmtt.fd) Runaway argument? f\left ( x\right ) =\left \{ \begin {array}[c]{ccc} -1 \@endpbox \hskip \ETC. ! Forbidden control sequence found while scanning use of \AltMathOne. <inserted text> \par l.10 -1 & & -\pi\leq x\leq0\\ ? ---------------------------- May be mathjax can not handle array inside table? Here is MWE and the command used to compile it -------------- \documentclass{article} %must include this, else make4ht gives error. Strange. \usepackage[export]{adjustbox} \usepackage{longtable} \begin{document} \begin{longtable}{|p{3in}|p{3in}|} A & $f\left( x\right) =\left\{ \begin{array}[c]{ccc} -1 & & -\pi\leq x\leq0\\ 1 & & 0<x\leq\pi \end{array} \right. $ \end{longtable} \end{document} ------------------------- Compiled with (all one one line) make4ht -ulm default foo1.tex "htm,notoc*,mathjax,p-width,charset=utf-8" " -cunihtf -utf8" When compiled with SVG, no error: make4ht -ulm default -f html5+dvisvgm_hashes foo1.tex "htm,pic-align,notoc*,p-width,charset=utf-8,svg" "-cmozhtf -utf8" I guess will switch to using SVG to compile this file for now. Is this mathjax issue or tex4ht? Using TL 2019 on Ubuntu under windows 10. Thanks --Nasser