Longtable Duplicate Separator at Page Break

Question

I have a longtable spreading over 2 pages. Unfortunately, since I decided to use the booktabs package, I get a duplicate line separator between the table header of the second page and the next table entry. I found solutions like adding a * behind the \\ but they didn't work.

I want to remove the annoying dashed line on the second page:

My minimal example:

\documentclass[a4paper, 12pt]{article}
\usepackage{longtable}
\usepackage{arydshln}
\usepackage{booktabs}

\begin{document}
\vspace*{17cm}

\begin{longtable}[c]{@{}llll@{}}\toprule
\# & A & B & C\\
\midrule
\endhead
1 & A & B & C \\
\hdashline
2 & A & B & C \\
\hdashline
A & A & B & C \\
\hdashline
3 & A & B & C \\
\hdashline
4 & A & B & C \\
\hdashline
5 & A & B & C\\
\hdashline
6 & A & B & C\\
\hdashline
7 & A & B & C \\
\bottomrule
\end{longtable}

\end{document}

Answer 1

Now you can try the new LaTeX3 package tabularray. It always uses \toprule, and \bottomrule in any table pages, and doesn't make duplicate line separators.

\documentclass{article}

\usepackage[paperwidth=8cm,paperheight=5cm,width=7cm,height=4.4cm]{geometry}
\usepackage{tabularray}
\UseTblrLibrary{booktabs}
\NewTableCommand{\hdashline}{\hline[dashed]}

\begin{document}

\begin{longtblr}[
  halign = c,
  caption = {Long Caption},
  label = {tblr:test},
]{
  colspec = {@{}XXXX@{}}, rowhead = 1,
}
\toprule
  \# & A & B & C\\
\midrule
  1 & A & B & C \\
\hdashline
  2 & A & B & C \\
\hdashline
  3 & A & B & C \\
\hdashline
  4 & A & B & C \\
\hdashline
  5 & A & B & C\\
\hdashline
  6 & A & B & C\\
\hdashline
  7 & A & B & C \\
\hdashline
  8 & A & B & C \\
\bottomrule
\end{longtblr}

\end{document}