% main.tex
\documentclass{scrbook}
% Uncomment this after aux files have been generated.
%\includeonly{}
\begin{document}

\include{footnote}

% If this is uncommented, the error does not occur.
%This is a\footref{fn} working footref.

\begin{figure}
	\centering
	\Large Float
	\caption{This is a\footref{fn} float.}
\end{figure}

This is a\footref{fn} working footref.

\end{document}
