Latest MiKTeX-Update broke XeLaTeX with fontspec

Question

I updated MiKTeX a few days ago and since then I cannot compile XeLaTeX with fontspec anymore.

\documentclass{article}
\usepackage{fontspec}

\begin{document}
Hello world!
\end{document}

When I try to compile it MiKTeX tells me that it expl3 is an unknown package. I cannot find this package in the Package Manager. Without the \usepackage{fontspec} the file compiles fine.

Any idea what I can do?

Answer 1

There has been a passing issue with way MiKTeX installs LaTeX3 support. Use the MiKTeX Package Manager to install the l3kernel and l3packages bundles, and at the same time remove expl3 and xpackages if they are installed.