Latex using foreign language results in error in citations - latex

Question

When including LaTeX foreign language packages:
\usepackage[utf8x]{inputenc}
\usepackage[english,hebrew]{babel}
\usepackage[top=2cm,bottom=2cm,left=2.5cm,right=2cm]{geometry}
I get an error for the citations:
Example:
Missing number, treated as zero.
<to be read again>
\afterassignment
l.19 ...{example1}}}{\##number {27}}
A number should have been here; I inserted `0'.
(If you can't figure out why I needed to see a number,
look up `weird error' in the index to The TeXbook.)
Another Example:
Improper alphabetic constant.
<to be read again>
\afterassignment
l.86 ...15normalized}. \citet{example2}
further improved the resu...
A one-character control sequence belongs after a ` mark.
So I'm essentially inserting \0 here.
! Missing = inserted for \ifnum.
<to be read again>
\afterassignment
l.86 ...15normalized}. \citet{example2}
further improved the resu...
I was expecting to see `<', `=', or `>'. Didn't.
And the citations are empty.
When I don't include the foreign language packages I don't get the error and the citations are great.
The format I used for citations is \usepackage{natbib} and for the document \documentclass[12pt,twoside]{mitthesis}.
I also tried other formats and get the same error.
bibliography.bib is traditional:
#article{example1,
title={Title1},
author={Author},
journal={arXiv preprint arXiv:1706.04902},
year={2019}
}
#article{example2,
title={Title2},
author={Author},
journal={arXiv preprint arXiv:1706.04902},
year={2019}
}
Minimal Working Example is super basic, (the minimal Not-Working Example is when you uncomment the Hebrew part):
\documentclass{report}
%\documentclass[12pt,twoside]{mitthesis}
\usepackage{natbib}
% Hebrew
% \usepackage[utf8x]{inputenc}
% \usepackage[english,hebrew]{babel}
% \usepackage[top=2cm,bottom=2cm,left=2.5cm,right=2cm]{geometry}
\begin{document}
%\selectlanguage{english}
\include{introduction} %some text with \cite{example1} and so on...
% bibliography
\bibliography{bibliography}
\bibliographystyle{plainnat}
\end{document}

Answer 1

To avoid the problems load natbib after babel:
\documentclass{report}
%\documentclass[12pt,twoside]{mitthesis}
% Hebrew
\usepackage[utf8]{inputenc}
\usepackage[english,hebrew]{babel}
\usepackage[top=2cm,bottom=2cm,left=2.5cm,right=2cm]{geometry}
\usepackage{natbib}
\begin{filecontents}{bibliography.bib}
#article{example1,
title={Title1},
author={Author},
journal={arXiv preprint arXiv:1706.04902},
year={2019}
}
#article{example2,
title={Title2},
author={Author},
journal={arXiv preprint arXiv:1706.04902},
year={2019}
}
\end{filecontents}
\begin{document}
% \selectlanguage{english}
\cite{example1,example2}
{
\selectlanguage{english}
\cite{example1,example2}
}
% bibliography
% \selectlanguage{english}
\bibliography{bibliography}
\bibliographystyle{plainnat}
\selectlanguage{english}
\bibliography{bibliography}
\bibliographystyle{plainnat}
\end{document}
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