longtable misplaced noalign

This isn't the answer to the original post, but I came here Googling for "Longtable misplaced noalign" so my eventual solution might be useful for someone.

In my case I needed a \\ after the \caption and \label. This seems incredibly counterintuitive to me so if anyone can explain why or tell me where this is documented I'd be grateful.

\documentclass{article}
\usepackage{booktabs}
\usepackage{longtable}
\begin{document}
\begin{longtable}{ll}
% Uncomment the \\ on the next line and the misplaced \noalign disappears!
\caption{Captions should appear on top of tables}\label{tbl:table}%\\
    \toprule
                  & foo \\
    \midrule
    \endfirsthead
    bar           & 1 \\
    baz           & 2 \\
    \bottomrule
\end{longtable}
\end{document}

All \nopagebreak's are undesired:

\documentclass{scrartcl}
\usepackage{longtable}
\usepackage{booktabs}

\begin{document}

\section{Table test}

\begin{longtable}{llc}
\hline
 &  & \multicolumn{1}{c}{All} \\ 
\hline
m & \rule{0pt}{1.7\normalbaselineskip}April  & $1$ \\
 &  July  & $1$ \\
 &  June  & $1$ \\
l & \rule{0pt}{1.7\normalbaselineskip}C  & $1$ \\
 &  F  & $1$ \\
 &  S  & $1$ \\
nums & \rule{0pt}{1.7\normalbaselineskip}28  & $2$ \\
 & 62  & $1$ \\
\hline 
\end{longtable}
\end{document}