Package natbib Error: Bibliography not compatible with author-year citations

Question

I have a basic tex file and a bibliography which is exported from Mendeley

However, when I want to cite in the author-year style, I get the error:

Package natbib Error: Bibliography not compatible with author-year citations. (natbib) Press <return> to continue in numerical citation style.

Any clue what's wrong?

Minimum working example:

\documentclass[letterpaper, 10pt]{article}

\usepackage[authoryear]{natbib}
\usepackage{lipsum}

\begin{document}

\lipsum[1-4]
\nocite{*}

\bibliographystyle{apalike}
\bibliography{articles}

\end{document} 

A snippet of my .bib library:

@article{shortcode,
author = {Lastname, Firstname},
file = {:/path/to/file.pdf:pdf},
journal = {Journal name},
number = {xx},
pages = {x--xx},
title = {Title},
volume = {xx},
year = {xxxx}    
}

Answer 1

Another way this error can arise is if one of your BibTeX entries has no year.

To find out which entry it is, look earlier in the output for a message like Warning--empty year in ABC2019. So check ABC2019.

Answer 2

When changing the bibliography style, sometimes natbib is upset because it can't interpret the data correctly.

In any case, after changing the argument to \bibliographystyle a run of LaTeX and one of BibTeX are necessary to get back in sync. Removing the .bbl and .aux files before those run is recommended, in order to avoid spurious error messages that might corrupt the .aux file currently being generated.

Answer 3

I had the same error trying to use spmpsci.bst in conjunction with natbib. While natbib's default citation style is author-year, spmpsci.bst is numeric, so this is a strange error to get. I eventually changed the following:

\usepackage[square,sort,comma]{natbib}

to

\usepackage[square,sort,comma,numbers]{natbib}

Problem went away.

Answer 4

The error occurs because natbib cannot find year information in the .bbl file (or possibly, but less likely, it cannot find author information). You can open it up yourself to see why this is the case.

The simplest reason would be that you have a \bibitem with the year field missing. A trickier reason is that your bibliography style does not output year information in a way that is parsable by natbib. For example, I was using \bibliographystyle{abbrv}, which does not play nicely with natbib. I fixed the problem by using instead \bibliographystyle{authordate1}. Of course, delete all temporary files, especially .bbl and .aux files, after making this change.

A final workaround is to use \usepackage[numbers]{natbib} when including the package. This outputs numbered citations instead of (author, year) citations and does not need year information.

Answer 5

Follow these steps:

1. Delete the .aux and the .bbl files
2. Do your changes (in the \bibliographystyle or in any option of natbib)
3. Run LaTeX
4. Run BibTeX

Answer 6

Another way this error can arise is if one of your BibTeX entries has no year. (From Josh Porter's answer)

This is true, but due to the mismatch between natbib package and your bibliographystyle settings, instead of a bug of natbib, which uses its own bibliography styles (even though natbib supports the original bibtex styles but not completely).

natbib intends to offer better author-year citations. If using natbib, you should choose plainnat, abbrvnat or unsrtnat. For example,

\documentclass[letterpaper, 10pt]{article}

\usepackage[round,sort]{natbib}
\usepackage{lipsum}

\begin{document}

\lipsum[1-4]

\bibliographystyle{abbrvnat}
\bibliography{articles}

\end{document} 

Here [round,sort] is not necessary, which makes it look close to APA style. If you want use IEEE-like style, you could use \usepackage[numbers]{natbib}.

However, if you use apalike, ieeetr, siam, etc., it implies you use the default bibtex styles, you should comment natbib package; otherwise, you would meet the problems if your bib files contain entries without author/year information.

Either way should solve your problem. This also brothers me for a long time, due to many incorrect examples in blogs.

References:

https://en.wikibooks.org/wiki/LaTeX/More_Bibliographies

http://sites.stat.psu.edu/~surajit/present/bib.htm#bibstyle

Answer 7

To add to the compendium of ways this error can occur, if you are using elsarticle.cls, do not use it with options

    \documentclass[authoryear]{elsarticle}

and the style

    \bibliographystyle{elsarticle-num}

Answer 8

In my case the problem was setting the cite style!!so, simply \setcitestyle{...}

Answer 9

Another not so intuitive reason for me was that I simply forgot a comma after one of the shortcodes. There was no other error and the references displayed fine, however only numerical.

Answer 10

This error occurs because of the conflict in how you define the citation style and the bibliography style. In your case, note that \usepackage[authoryear]{natbib} is same as \usepackage{natbib} while the 'biblographystyle' is defined as \bibliographystyle{apalike} meaning it is plain, basically 'numbers'.

Therefore, just change

\usepackage{natbib}

to

\usepackage[numbers]{natbib}

Answer 11

This can also happen if one of the BibTeX entries is missing the label (shortcode).

One possible scenario is when the bibliography is exported from e.g. EndNote and the label for the entry has not been set in EndNote. (This happened to me.)

Answer 12

Don't use natbib in Beamer! Plus: possible solution

Another possibility: I have got the same errors when trying to use natbib in Beamer class (for presentation). The following two lines handles references properly:

\usepackage[style=authoryear]{biblatex}
\bibliography{bib.bib}

Answer 13

I had similar problem and it was over when I removed the option [authoryear]. Hope it works with you.