Bold sans-serif font in LaTeX

Question

How can one format a chapter or section heading in bold using a sans-serif font? I tried \textsf{\textbf{bold sans-serif text}}, but it does not seem to work. Any idea?

Answer 1

It looks like you are trying to change the sections font to sans serif and usual bold letters. If you want it to be in sans serif through out the document, then you can do it with sectsty package.

\documentclass{article}
\usepackage{sectsty}
\allsectionsfont{\bfseries\sffamily} % <---- omitting \bfseries still gives bold font
\begin{document}
\section{Section}
\section{Section}
\end{document}

Edit: For only one chapter the code can be modified like this.

\documentclass{book}
\usepackage{sectsty}
\begin{document}
\chapter{first}
\section{Section}
This is one section.
\section{Section}
This is another section.
\chapter{second}
%\sectionfont{\sffamily} for only sections in sf
\allsectionsfont{\sffamily} %<-----command here. use \sectionfont{\sffamily} for only sections
\section{Section}
This is one section.
\subsection{Subsection} A sub section
\section{Section}
This is another section.
\allsectionsfont{\rmfamily} %%<-----command here
\chapter{Third}
\section{Section}
This is one section.
\section{Section}
This is another section.
\end{document}

Please look into the documentation of sectsty for details

Answer 2

The following minimal example compiles without any errors or warnings:

\documentclass{article}
\begin{document}
\textbf{This is bold text.}
\textsf{This is sans-serif text.}
\textsf{\textbf{This is sans-serif bold text.}}
\textbf{\textsf{This is bold sans-serif text.}}
\end{document}

Note that both \textsf{\textbf{...}} and \textbf{\textsf{...}} both work, and both have the exact same effect. But if one order is not working for you, maybe try the other?

You should compare your document to this minimal example and see if you have used any packages or defined any macros which may have changed the way \textsf and/or \textbf operate. (It's also possible that your fonts are not compatible with one of these commands.) To isolate the problem, try starting from a minimal document in which this formatting works, and then keep adding the packages and macros you use until the error comes up.