I'm using the IET template(https://digital-library.theiet.org/journals/author-guide). The error information also tell incompatible with natbib? Can anyone help me? Thanks a lot!

\documentclass{cta-author}

\usepackage{subfig}
\usepackage{diagbox}
\usepackage{multirow}
\usepackage{multicol}
\usepackage{graphicx}
\usepackage{booktabs}
\usepackage{biblatex}

\newtheorem{theorem}{Theorem}{}
\newtheorem{corollary}{Corollary}{}
\newtheorem{remark}{Remark}{}

\begin{document}

\bibliographystyle{iet}
\bibliography{aaa}

\cite{boulkenafet2017face}

\end{document}


• Welcome to TeX.SE! You can not use biblatex together with \bibliographystyle. Simply comment biblatex in your code ... – Mensch Apr 15 at 10:27
• Related (half-duplicate): tex.stackexchange.com/q/439309/35864 – moewe Apr 15 at 10:45

With a newer version of biblatex the first error I get from your example is slightly more helpful than the errors shown in your screenshot.

! Package biblatex Error: Incompatible package 'natbib'.

See the biblatex package documentation for explanation.
Type  H <return>  for immediate help.


The class cta-author loads natbib for citations and the bibliography. (The example file then proceeds to add the references manually in thebibliography and does not provide any author-year metadata in a natbib-readable format, so the class does not make use of many of natbib's most valued functions, but the package is still loaded.) natbib and biblatex are completely incompatible and can not be used together in the same document. Since your template loads natbib, the viable option is to stop using biblatex. Indeed, not a lot of publishers are known for accepting biblatex submissions and biblatex usually requires a different workflow (Biblatex: submitting to a journal).

In the example it should be enough to drop biblatex to make it work again (assuming you have the file iet.bst).

\documentclass{cta-author}

\usepackage{subfig}
\usepackage{diagbox}
\usepackage{multirow}
\usepackage{multicol}
\usepackage{graphicx}
\usepackage{booktabs}

\newtheorem{theorem}{Theorem}{}
\newtheorem{corollary}{Corollary}{}
\newtheorem{remark}{Remark}{}

\begin{document}

\bibliographystyle{iet}
\bibliography{aaa}

\cite{boulkenafet2017face}

\end{document}