# titlesec 2.10.1 seems to completely break \section

Here's my testcase:

\documentclass[12pt,english]{scrartcl}
\usepackage{titlesec}

\begin{document}
\section{Foo}
\end{document}


Using "pdfTeX 3.14159265-2.6-1.40.16 (TeX Live 2015)" and titlesec 2.10.1, this doesn't build:

! Missing number, treated as zero.
}
l.5 \section{Foo}


It builds if I comment out the \usepackage line.

Both build fine in "pdfTeX using libpoppler 3.141592-1.40.3-2.2 (Web2C 7.5.6)" and titlesec 2.6.

What's going on?

• titlesec 2.10.1 is buggy and has an update already since 2016/21/03, version 2.10.2 (and what @StevenB.Segletes noted about KOMA and titlesec ;-)) – user31729 Mar 30 '16 at 13:30
• It works for me. But are you aware of the log warning? Class scrartcl Warning: Usage of package titlesec together with a KOMA-Script class is not recommended. I'd suggest to use the package only if you really need it, because it breaks several KOMA-Script features, i.e., option headings' and the extended optional argument of the section commands. – Steven B. Segletes Mar 30 '16 at 13:30
• @StevenB.Segletes: Indeed – Lightness Races in Orbit Mar 30 '16 at 13:32
• See komascript.de/titlesec (German). The new titlesec version 2.10.2 does not work with KOMA version 3.19a. You have to install the prerelease of 3.20 from komascript.de/node/1801. But not that it is not recommended to use titlesec together wirh a KOMA-Script class. – esdd Mar 30 '16 at 13:39
• @esdd: I suspect ultimately I'll stop using KOMA-Script and go back to article, but for now I'd just like to get my documents building again with a minimum of changes. :) I'm rebuilding my environment to pull down titlesec 2.10.2. Hopefully my KOMA isn't 3.19a. – Lightness Races in Orbit Mar 30 '16 at 13:41

This is broken in 2.10.2 too, but can be resolved by switching to the article` class. Apparently this is one of those times that a compatibility warning ought to be heeded.