# Hyperref Warnings

Overleaf tells me this:

Why? Thank you so much

First Edit: (Reading comment) A short tex-code from Overleaf and just edited by me:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Welcome to Overleaf --- just edit your LaTeX on the left,
% and we'll compile it for you on the right. If you open the
% 'Share' menu, you can invite other users to edit at the same
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\documentclass{book}
\usepackage{blindtext}
\usepackage{hyperref}

\author{Overleaf}

\begin{document}

\frontmatter
\tableofcontents
\clearpage

{\huge {\bf Foreword}}

\Blindtext
\clearpage

{\huge {\bf Dummy entry}}

\Blindtext
\mainmatter

\chapter{First Chapter, $a=b$}

This will be an empty chapter

$$\label{eq:1} \sum_{i=0}^{\infty} a_i x^i$$

The equation \ref{eq:1} shows a sum that is divergent. This formula will be used later on page \pageref{second}.

\Blindtext
\clearpage

\section{Second section} \label{second}

\blindtext
\Blinddocument
\end{document}

• Do you have section titles containing 'special' symbols? I think I had this problem once when I used \, in a section title. I think PDFs aren't able to handle this special symbol. Try to find out what causes this problem, and then use \texorpdfstring. Note: Maybe I am completely wrong. Jul 27, 2021 at 11:22
• A think like \section{$x^2$} can cause similar warnings as it cannot convert $x^2$ to something that the bookmarks can understand. Thus use use \texofpdfstring{for text}{for bookmarks} to help it. Without showing us more about what is triggering this, we cannot help much. Exactly what do you have that causes \hskip 14.4pt? Jul 27, 2021 at 11:38
• the first warning means that you aren't using headings in the right order, you have e.g. somewhere a \section followed by a \paragraph. The second means that you have in a heading or caption a space command like \quad, the third that you have math. For both you can use something like \texorpdfstring{$a=b$}{version for bookmarks e.g. a=b} to help hyperref. Jul 27, 2021 at 11:39
• Please, can you add a full minimal compilable code? I like the orange but the size of the characters are very tiny :-( Jul 27, 2021 at 11:39
• Please, consider that \bf and the similar commands have been deprecated for almost 30 years. Jul 27, 2021 at 14:38

Unfortunately your code does not create similar errors like you posted, at least in my environment. It may be because you did not use hyperref at all ind the code snippet.

If I go through each warning I've got and "cure" it, I end up with this one, taking some comments made into account:

\documentclass{book}
\usepackage{blindtext}
\usepackage{hyperref}

\author{Overleaf}

\begin{document}

\frontmatter
\tableofcontents
\clearpage

{\huge {\bf Foreword}}

\Blindtext
\clearpage

{\huge {\bf Dummy entry}}

\Blindtext
\mainmatter

\chapter{First Chapter, equality}% <<==

This will be an empty chapter

$$\label{eq:1} \sum_{i=0}^{\infty} a_i x^i$$

The equation \ref{eq:1} shows a sum that is divergent. This formula will be used later on page \pageref{second}.
\Blindtext
\clearpage

\section{Second section} \label{second}

\blindtext
\Blinddocument
\end{document}


Screenshot:

To localize the source of your warnings I suggest a "homing-in" strategy. I.e. delete one half of your relevant text, rund + check, restore, delete other half, run + check. If you do it right, i.e. matching your situation, one half should pass, while the other will fail. Repeat. // Consider "halfness" as a fuzzy concept. It can be really 50 %, or more, or less. Because you follow a $2^n$ scheme, you should quickly arrive at the trouble-makers.