On 2013–03–01 Alasdair McAndrew wrote:

> Arrgh: more problems.  I've downloaded and installed context standalone
> (version 2013.02.26 00:17).  Now when I run context I get an error (for the
> first time ever) when it reaches a chapter heading:
> 
> l.1 ...[ch:this]{My first chapter}
> 
> ? h
> The lua interpreter ran into a problem, so the
> remainder of this lua chunk will be ignored.
> 
> I have the following setups:
> 
> \def\chap#1#2{\vbox{\darkgreen Chapter
> #1\crlf\framed[frame=off,topframe=on]{#2}}}
> \def\uchap#1#2{#2}
> 
> \setuphead[chapter][command=\chap,style=bfd,after={\blank[1cm]},textcolor=darkgreen,numbercolor=darkgreen]
> 
> None of this has ever given me any problems before.

It's easier to tell with a minimal example. But here's a guess. Try

  \unexpanded\def#1#2\chap{…}

or

  \define[2]\chap{…}


Marco