This could mean you have an emacs that was not compiled with libxml.

Type C-h v system-configuration-options

and look for --with-xml2

to see if your emacs was built with it.
John

-----------------------------------
Professor John Kitchin (he/him/his)
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803


On Mon, Oct 18, 2021 at 4:12 AM Timothy <tecosaur@gmail.com> wrote:
Hi Joseph,

The function libxml-parse-xml-region has been around for a while, what version
of Emacs are you running?

All the best,
Timothy