First reported at tex4ht mailing list: reference link:
http://tug.org/pipermail/tex4ht/2015q3/001240.html

When compiling the following MWE and asking tex4ht to use SVG for math, it reports missing fonts

---------------------------------------
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{ntheorem}
\newtheorem{theorem}{Theorem}
\usepackage{amsmath}
\DeclareMathOperator{\Res}{Res}
\usepackage{kpfonts}

\begin{document}
\ifdefined\HCode
\Configure{Picture}{.svg}
\fi

\begin{theorem}[Residue Theorem]
Let $f$ be analytic in the region $G$ except for the isolated
singularities $a_1,a_2,\dots,a_m$. If $\gamma$ is a closed
rectifiable curve in $G$ which does not pass through any of the
points $a_k$ and if $\gamma\approx 0$ in $G$, then
\[
\frac{1}{2\pi i}\int_\gamma\! f = \sum_{k=1}^m
n(\gamma;a_k)\Res(f;a_k)\,.
\]
\end{theorem}
\end{document}
\end{document}
------------------------------

compile using htlatex foo.tex gives

warning --- Couldn't find font `jkpsy.htf' (char codes: 0--128)
warning --- Couldn't find font `jkpmi.htf' (char codes: 0--239)
warning --- Couldn't find font `jkpmi.htf' (char codes: 0--239)
warning --- Couldn't find font `jkpmn7t.htf' (char codes: 0--170)
warning --- Couldn't find font `jkpmn7t.htf' (char codes: 0--170)
warning --- Couldn't find font `jkpbn8t.htf' (char codes: 0--255)
warning --- Couldn't find font `jkpmit8t.htf' (char codes: 0--255)
warning --- Couldn't find font `jkpmn8t.htf' (char codes: 0--255)

Compiling to png works ok, i.e. when replacing the line
\Configure{Picture}{.svg}
with
\Configure{$}{\PicMath}{\EndPicMath}{}

But math looks better in SVG.
Tl 2015.