How to go around the error "! Package xkeyval Error: `[' undefined in families `background'."?

Question

I get the error

! Package xkeyval Error: `[' undefined in families `background'.

when processing the file

\documentclass{article}

% \usepackage{xkeyval} 
% \usepackage{pax}
% \usepackage{pdfpages}
% 
% \makeatletter
% \define@key{PAX@Gin}{scale}{}
% \makeatother

\usepackage{background}
\backgroundsetup[contents=preliminary,placement=bottom,color=blue]

\usepackage{lipsum}
\begin{document}
\lipsum[1-10]
\end{document}

using pdflatex. The version is:

pdfTeX 3.1415926-2.5-1.40.14 (TeX Live 2013)

Uncommenting the lines in the file (as per this post) does not solve the problem. Can you see what is wrong and how to solve it?

Answer 1

It should be

\backgroundsetup{contents=preliminary,placement=bottom,color=blue}

Note the delimiters { and } instead of [ and ].

\documentclass{article}

\usepackage{background}
\backgroundsetup{contents=preliminary,placement=bottom,color=blue}

\usepackage{lipsum}
\begin{document}
\lipsum[1-10]
\end{document}