# A confused compile error

fontspec-xetex.sty 1767
Forbidden control sequence found while scanning use of \__cs_generate_from_si
gnature:nnNNNn.
<inserted text>
\par
l.1767       \int_case:nnn


What's wrong with it ? Is there any change in this file ?

In the console-output window,the error is like this:

Runaway argument?
{\dim_set:Nn ##1{\fontdimen ##2##3}\dim_compare:nNnT ##1={0pt}{\settoheight \ET
C.
! Forbidden control sequence found while scanning use of \__cs_generate_from_si
gnature:nnNNNn.
<inserted text>
\par
l.1767       \int_case:nnn
#2
?


• you have a Runaway argument? so you have (or tex thinks you have) a missing }` somewhere in your source so tex can not find the end of an argument, but as you do not show any input it is hard to say exactly what is wrong. – David Carlisle Apr 17 '17 at 9:32