Conflict between tabu and tabularx, when using siunitx
tabularx
is redefining \arraybackslash
(and it even tells in the docu that this is a hack:
\arraybackslash \\ hack.
\def\arraybackslash{\let\\\@arraycr}
tabu
doesn't like this definition. It expect \arraybackslash
to have the meaning from array.sty
. So now \\
gives errors. You can give \arraybackslash
locally the standard definition back:
\begingroup
\def\arraybackslash{\let\\\tabularnewline}
\begin{longtabu}
....
\end{longtabu}
\endgroup
I'm not sure what tabu
is doing here (I didn't have it installed prior to this) but it looks like something is locally defining \\
so it no longer ends the table row. using \tabularnewline
instead seems to make your example work.