Hi Nasser, this is not limited to TeX4ht but to l3regex, which is used to clean the MathJax code. See this question, where they found the same issue: https://tex.stackexchange.com/q/654633/2891

In theory, you could skip the regex cleaning using this configuration file:

%%%%%%%%%%%%%%%%
\Preamble{xhtml}
\ExplSyntaxOn
\cs_set_protected:Npn \alteqtoks #1
{
\HCode{\detokenize{#1}}
}
\ExplSyntaxOff
\begin{document}
\EndPreamble
%%%%%%%%%%%%%%%%%%%%%

The downside is that you can end with incorrect characters in your HTML, in particular <, > and &. These can cause MathJax fail.

Also, to break your long strings, you can use this prefilter:

%%%%%%%%%%%%%%%
local max_len = 255
for line in io.lines() do
line = line:gsub("\r", "")
local str_len = string.len(line)
if str_len > max_len then
-- if the line is longer than maxlen, we will break it to a shorter segments
local curr_pos = max_len
local prev_pos = 1
while curr_pos < str_len do
-- find next command preceded by spaces starting at the current position
curr_pos, len = string.find(line, "%s+\\", curr_pos)
print(curr_pos, str_len,string.sub(line, prev_pos, curr_pos))
prev_pos = curr_pos
-- we must move the current position
curr_pos = curr_pos + max_len
end
-- print rest of the line
print(string.sub(line, prev_pos, str_len))
else
print(line)
end
end

%%%%%%%%%%%%

Use it as:

$ texlua format.lua < original.tex > formated.tex

It will format your long lines into much shorter chunks, preventing the "! Unable to read an entire line---bufsize=200000" error I encountered. I suppose that you set the limit higher, but I didn't and couldn't compile your file originally.

Is there a way to fix this issue?

(/usr/local/texlive/2023/texmf-dist/tex/latex/l3backend/l3backend-dvips.def)
No file A.aux.
(/usr/local/texlive/2023/texmf-dist/tex/latex/base/ts1cmr.fd)
! Bad register code (65536).
\__tl_analysis_a_space_test:w ...alysis_index_int
{\exp_not:n { }}\__tl_anal...

l.53 \]

This happens only when using texht.

The Latex is auto-generated by Maple. I know it is due to one or few lines too long. But it is impossible to edit by hand, since the program generated this automatically using Maple each time it is run.

Why lualatex handles it OK but not tex4ht? Is there a way to edit some configuration to make tex4ht not give this error?

Since the equations are large, I put everything in zip file including the maple style file used.

The command to generate the error is

make4ht -ulm default -a debug A.tex 'mathjax,htm,nostyle'

The zip file is

https://12000.org/tmp/bad_register_code_tex4ht.zip

When unzipping it will create folder bad_register_code_tex4ht where all the files are there (A.tex and maple style file).

I am using texlive 2023 on Linux.

I hope there is a solution to this, otherwise I will no longer be able to build to HTML now.

Thanks
--Nasser