This question evolved from my earlier question posted here. It turnt out that what I gave as the MWE actually worked, so I investigated a bit and found the real problem.
I have a document in which I generally do not want to number the chapters, sections and subsections. Only one section should contain roman numbered subsections. Considering the following code:
\documentclass{report}
\usepackage{titlesec}
\titleformat{\subsection}{\normalsize\bf\it}{}{}{}
\setcounter{secnumdepth}{-1}
\begin{document}
\tableofcontents
\chapter{mwe}
\section{unnumbered subsections}
\subsection{unnumbered}
\section{roman numbered subsections}
\setcounter{secnumdepth}{2}
\renewcommand{\thesubsection}{\textnormal{\roman{subsection}}.}
\subsection{roman one}
\subsection{roman two}
\setcounter{secnumdepth}{-1}
\chapter{Second chapter}
\section{unnumbered subsections}
\subsection{unnumbered}
\end{document}
which is the solution from my earlier post adding the titlesec package and modifying the subsection's title (i.e. lines 2&3). Here I get the 'Missing number treating as zero' error at the line '\subsection{roman one}'. Can anybody tell me why and a fix or work-around?
Best Answer
The fourth mandatory argument of
\titleformat
must not be empty; you can useTaking into account a comment, perhaps you're trying to do something like this