When uploading an article written in latex to arXiv, it is very troublesome because the . Bib file cannot be used as a reference. The main reason is that the macro package - usepackage {natbib} will report an error With the help of overleaf, you can get an answer, that is, first download and package all the things needed for the whole latex compilation, and it’s better to compile locally, and then replace the references in . BBL with the contents in . Tex , that is

	%\bibliographystyle{unsrt}
	%\bibliography{refs}

At this time, it is OK locally, but not arXiv. The following steps are needed:
1. Comment out
2. Comment out the following part in . Sty file:

% load natbib unless told otherwise
% \if@natbib
%   \RequirePackage{natbib}
% \fi