Dear Scott, This breaks because of luainputenc, which you should not be using in the first place. It makes all kinds of Unicode characters active which blows up when building character tables in expl3. If you insist on using luainputenc, you have to change the order of loading packages, like in the MWE below. My advice is to just remove luainputenc, because recent LaTeX switches to UTF-8 by default and actually does the right thing.
Cheers, Henri
---
\documentclass[english]{article}
\usepackage{lmodern}
\usepackage[LGR,T1]{fontenc}
\usepackage{xfrac}
\usepackage[utf8]{luainputenc}
\begin{document}
\sfrac{A}{\kern-.08em S}
\end{document}
On 9/10/19 8:27 AM, Scott Kostyshak wrote:> Hi,
>
> I get an error when compiling the attached example file with LuaTeX on
> an updated TL 2019 system. I also attach the log, which contains the
> following error:
>
> ! Undefined control sequence.
> \GenericError ...
> #4 \errhelp \@err@
> ...
> l.27238 }
>
> ? X
>
> I don't know much about TeX (or LuaTeX), but the example file used to
> compile on an older TL version. Is the example now invalid?
>
> Best,
>
> Scott
>
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