# Incompatibility of scrbook and fontspec in TeX-Live 2013

Since updating to TeX-Live 2013 I am facing the following error:

Compiling the following file by XeLaTeX ...

\documentclass{scrbook}
\usepackage{fontspec}
\begin{document}
bla
\end{document}


... ends up with

! Undefined control sequence.
<argument> \str_if_eq_x_p:nn

l.5 \end{document}


Replacing scrbook by scrartcl or scrreprt works smoothly. Also in my old TeX-Live 2012 installation the problem does not occur.

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You have mismatched versions of fontspec and l3kernel (expl3): nothing to do with KOMA per se (probably showing up as a different path is taken in the code). Can you post your log file as an edit? –  Joseph Wright Jun 21 at 14:04
Oh my goodness. I happened to have all the l3-packages in my \$(HOME)/texmf file. Therefore the version mismatch occured. I could have figured this out myself by checking the logfiles more carefully. Thanks so much, problem solved. –  Johannes Jun 21 at 14:10
I suspected something like that: this is quite a common one :-) –  Joseph Wright Jun 21 at 14:10