I find that in the presence together of packages hyperref and xeCJK, in either order, raises an Improper alphabetic constant error with an em-dash in commands \section, \subsection, etc. This happens ...
I started using XeTeX and whenever I use the xeCJK package I get the following error: ! Critical xeCJK error: "l3-too-old" ! ! ! Support package 'expl3' too old. ! ! Please update an up to date ...