# fontspec fails after MikTeX Update on Windows 10 x64

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}
``````

``````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?

• Update l3kernel – Will Robertson Feb 18 at 3:18
• @WillRobertson l3kernel, l3packages, and l3experimental are all installed (according to MikTeX Console). Is there something else I need to do to update them? – Blake Lucas Feb 18 at 4:15
• Sorry for my terse reply above, was in a rush. Sorry to hear you had to go to rather extreme lengths to fix the problem... – Will Robertson Feb 18 at 10:29