[Tex/LaTex] compiler complains about apacite – Undefined control sequence. \st@rtbibchapter

Question

I use the following code in my document:

\documentclass{article}
\usepackage[utf8]{inputenc}                     
\usepackage[english]{babel}
\usepackage[square]{natbib}
\usepackage[colorinlistoftodos]{todonotes}
\usepackage[natbibapa]{apacite}    

\begin{document}
\selectlanguage{english}

\bibliographystyle{apacite}
\bibliography{bibliography}

\end{document}

Adding the package

\usepackage[natbibapa]{apacite}

results in a bunch of errors starting with

Undefined control sequence. \st@rtbibchapter
Too many }'s. }
Undefined control sequence. \bibliographytypesize

I have not used appacite before. I updated my packages with the MiKTeX Updater. Earlier questions like "compiler complains about apacite" were not able to help me.

Do you have any idea where the problem is?

Answer 1

Don't load natbib, apacite will do it in the correct way:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
%\usepackage[square]{natbib}
\usepackage[colorinlistoftodos]{todonotes}
\usepackage[natbibapa]{apacite}

\begin{document}
\selectlanguage{english}
\cite{doody}
\bibliographystyle{apacite}
\bibliography{biblatex-examples}

\end{document}