"Citation X on page X undefined on input line X" error with super minimal example

Question

I'm getting a Citation 'test' on page 1 undefined on input line 6. error for the below example on Overleaf.

I've looked at many other questions and I can't find the error. Any ideas?

\documentclass{article}
\usepackage{biblatex}
\begin{document}
\cite{test}
\begin{thebibliography}{99}
\bibitem{test} bibtest
\end{thebibliography}
\end{document}

Don't load biblatex, if you use a manual thebibliography environment to make your bibliography. — cabohah, May 11 '23 at 05:37
I agree that https://tex.stackexchange.com/q/630571/35864 is basically the same problem, but the question here is so much clearer (with a much better MWE) that it might be better to leave this one here open. — moewe, May 11 '23 at 08:11
I agree with @moewe that this question is more clear. I suggest we close the older question as a duplicate of this one. Maybe moewe as a gold badge holder could do that? — Marijn, May 11 '23 at 15:49

cabohah · Accepted Answer · 2023-05-11T06:07:33.517

biblatex requires another data format with\refsection, \datalist, \entry and \field etc., but not a thebibliography environment with \bibitem. So loading package biblatex but using a thebibliography environment — either manually edited or created by bibtex with another document — does not work.

In other words: You cannot mix the package with a manually created thebibliography environment. Instead you should use a bib file and run biber:

\documentclass{article}
\usepackage{biblatex}
\addbibresource{biblatex-examples.bib}
\begin{document}
Test: \cite{aksin}, \autocite{aksin}, \parencite{aksin}, \footcite{aksin} (the last one is nonsense with the default cite style, but could be useful, e.g., with \texttt{cite=authoryear} option).
\printbibliography
\end{document}

or manually:

\documentclass{article}
\begin{document}
\cite{test}
\begin{thebibliography}{99}
\bibitem{test} bibtest
\end{thebibliography}
\end{document}

If you are interesting in converting an already existing thebibliography environment into a bib file, see: Convert from a textplain reference to bibtex.

score 0 · Answer 2 · answered May 11 '23 at 05:57

As caboah told you, your MWE works without biblatex:

\documentclass{article}
\begin{document}
\cite{test}
\begin{thebibliography}{99}
\bibitem{test} bibtest
\end{thebibliography}
\end{document}

If you would like to use biblatex, you have to create a .bib file, for example mybib.bib:

@article{test,
    title={This is a test},
    author={Paulinho, van Duck},
    journal={Quack University Journal},
    volume={10},
    pages={16--30},
    date={2023-03-11},
    url={https://www.quackforyou.com}
}

and then add it to your document with \addbibresource{mybib.bib}:

\documentclass{article}
\usepackage[english]{babel}
\usepackage{csquotes}
\usepackage{biblatex}
\usepackage{xurl}
\usepackage{hyperref}
\addbibresource{mybib.bib}
\begin{document}
\cite{test}
\printbibliography 
\end{document}

"Citation X on page X undefined on input line X" error with super minimal example

2 Answers2