# Package hyperref Warning: Token not allowed in a PDF string?

I am using this package https://www.ctan.org/pkg/abntex2 and it is making my bibliography throws this warning:

[Compiling D:\User\Downloads\test.tex]

Basic Builder: running pdflatex...done.

No errors. Warnings:

D:\User\Downloads\test.tex: LaTeX Warning: File mybib.bib' already exists on the system.
D:\SublimeText\Data\Cache\LaTeXTools\b67b3be3974e1b01afc0a6dc77e46832\test.bbl:1: Package hyperref Warning: Token not allowed in a PDF string (PDFDocEncoding):(hyperref)                removing \uppercase' on input line 1.


This is a minimal example:

\documentclass[]{abntex2}

\begin{filecontents}{mybib.bib}

@misc{EXEMPLO,
author = {Ingo Lutkebohle}
}

\end{filecontents}

\begin{document}

test. \cite{EXEMPLO}

\bibliographystyle{abbrv}
\bibliography{mybib}

\end{document}


Related questions:

• This class is very badly written. Its authors do not know very basic stuff about writing classes/packages. As I said before, you do not want to use this class unless you have to. You certainly don't want to use it for your thesis. It will throw up all kinds of weird and mysterious problems which will be difficult to debug and address. The problems will increase exponentially if you have forked the class unless you know enough to rewrite all the problematic bits. But if you knew enough to do that, you would not fork this (or any) class. – cfr Aug 9 '17 at 1:25

\uppercase is not supported when a string is expanded for bookmarks. Either ignore the warning or add in the preamble:
\pdfstringdefDisableCommands{\let\uppercase\relax}

• Where is that coming from? The \cite command? – cfr Aug 9 '17 at 1:27