I have just updated my MikTeX installation to 2.9.6942 and Tex Studio to 2.12.14. I'm running on Windows 10 64-bit. The following code is in just about everything I write in LaTeX and it now breaks
\documentclass[12pt]{scrartcl}
\usepackage{fontspec}
\setmainfont{Times New Roman}
\addtokomafont{dispostion}{\rmfamily}
From the log in TeX Studio:
Undefined control sequence. \setmainfont{Times New Roman}
From the output messages:
Couldn't open `Times New Roman{}{}{.cfg' hbf2gf (CJK ver. 4.8.4)
From the actual log file:
! Undefined control sequence.
\__fontspec_init_ttc:n #1->\str_if_eq:eeT
{\str_lower_case:f {\l__fontspec_e...
l.4 \setmainfont{Times New Roman}
Everything is up to date, Times New Roman is installed, and I have successfully used it like this in versions past (MikTeX 2.9.6161). All L3 packages are installed as well. How do I get fontspec to work again?