Error using hyperref and tex4ebook

Question

\documentclass[ebook,12pt,oneside,openany]{memoir}
\usepackage[utf8]{inputenc}
\usepackage{graphicx}
\usepackage{xurl}

\usepackage[hyperindex=true]{hyperref}
\hypersetup{
    colorlinks   = true, %Colours links instead of ugly boxes
    urlcolor     = blue, %Colour for external hyperlinks
    linkcolor    = blue, %Colour of internal links
    citecolor   = red %Colour of citations
}
\title{Test}
\author{Author}
\date{}

\begin{document}

    \maketitle  
    \frontmatter    
    \tableofcontents \newpage   
    \mainmatter     
    \pagenumbering{arabic}

    \chapter{New Chapter}
    I am citing a book \footnote{sample footnote}.


    \backmatter     
\end{document}

I get following error message.

! LaTeX Error: No counter 'Hfootnote' defined.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                      

My .mk4 file is as follows:

Make:htlatex {}
Make:htlatex {}

Answer 1

There is a clash between Memoir, Hyperref and tex4ht in a definition of footnotes. The simplest fix is to define the Hfootnote counter in tex4ht. This can be done in a custom configuration file. Save the following code as mycfg.cfg:

\Preamble{xhtml}
\makeatletter
\@ifpackageloaded{hyperref}{%
\ifHy@hyperfootnotes
\newcounter{Hfootnote}
\fi
}{}
\makeatother
\begin{document}
\EndPreamble

Request the config file using

tex4ebook -c mycfg.cfg filename.tex

The compilation should run without errors.