It seems that Miktex is still not updated. There it also some strange bug that happens with tex4ebook: https://tex.stackexchange.com/q/563644/2891

Possibly related to #475. The following text is adapted from my question in the Tex StackExchange.

I'm running a document which compiles to HTML using make4ht + LuaLaTeX.

When testing both on Ubuntu, it works flawlessly, but when the same document is ran on Windows 10 with MiKTeX, I get a bunch of `"Unsupported font"` errors.

While making a minimal example, I realized this only happened when I imported the `polyglossia` package.

A minimal example of such document:

    \documentclass{article}
    
    \usepackage{polyglossia}
    
    \begin{document}
    Hello world
    \end{document}

    $ make4ht -l document.tex

Gives:

[STATUS]  make4ht: Conversion started
[STATUS]  make4ht: Input file: prueba.tex
This is LuaTeX, Version 1.12.0 (MiKTeX 20.7)
 restricted system commands enabled.
Unsupported font        [lmroman10-regular]:+tlig;
This is LuaTeX, Version 1.12.0 (MiKTeX 20.7)
 restricted system commands enabled.
Unsupported font        [lmroman10-regular]:+tlig;
This is LuaTeX, Version 1.12.0 (MiKTeX 20.7)
 restricted system commands enabled.
Unsupported font        [lmroman10-regular]:+tlig;

# (a bunch of debugging from the document iself)

----------------------------------------------------
--- error --- Can't find/open file `[lmroman10-regular]:+tlig;.tfm'
[FATAL]   make4ht-lib: Fatal error. Command tex4ht returned exit code 1

This is a fresh installation of Windows 10 running latest MiKTeX, installed directly from their website. The command was run under PowerShell. The full output of make4ht can be found on this gist.

I've tried changing fonts with no luck, as well as playing with MiKTex settings.