Here is an MWE
\documentclass{article}
\usepackage{tikz,pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}[unbounded coords=jump, stack plots=y]
\addplot[fill=gray, draw=black] table[]{123.tsv}
\closedcycle;
\addplot[fill=none, draw=black] table[]{123.tsv}
\closedcycle;
\end{axis}
\end{tikzpicture}
\end{document}
my data looks like this
1 nan
1.2 0.2
0.9 0.1
running the above produce the error: Undefined control sequence. [\closedcycle;]
Ulrike Fischer suggested that some definitions went missing.
I have opened a bug on pgfplots because it's not clear where it belongs.
https://sourceforge.net/p/pgfplots/bugs/219/
For details see https://github.com/pgf-tikz/pgf/issues/511