Hi

I am running emacs 29 and org mode 9.6.9

I have set (setq org-latex-line-break-safe "\\\\")

Nevertheless the following example 
#+begin_src 
#+ATTR_LATEX: :environment longtable
| / |  <> |        <> | <>           | <>           | <>           | <>           | <>           |
|---+-----+-----------+--------------+--------------+--------------+--------------+--------------|
|   | Num | Documento | <2024-04-26> | <2024-04-29> | <2024-05-06> | <2024-05-08> | <2024-05-10> |
|---+-----+-----------+--------------+--------------+--------------+--------------+--------------|
|   |   1 |  12345678 |              |              |              |              |              |
|   |   2 |  12345678 |              |              |              |              |              |
|   |   3 |  12345678 |              |              |              |              |              |
|   |   4 |  12345678 |              |              |              |              |              |
#+end_src

Will be translated to 

#+begin_src 

\begin{longtable}{|r|r|l|l|l|l|l|}
\hline
Num & Documento & \textit{26.04.2024} & \textit{29.04.2024} & \textit{06.05.2024} & \textit{08.05.2024} & \textit{10.05.2024}\\ \hline
\hline
\endfirsthead
\multicolumn{7}{l}{Continued from previous page} \\ \hline[0pt]
\hline

Num & Documento & \textit{26.04.2024} & \textit{29.04.2024} & \textit{06.05.2024} & \textit{08.05.2024} & \textit{10.05.2024} \\ \hline[0pt]

\hline
\endhead
\hline\multicolumn{7}{r}{Continued on next page} \\ \hline
\endfoot
\endlastfoot
\hline
1 & 12345678 &  &  &  &  & \\ \hline
2 & 12345678 &  &  &  &  & \\ \hline
3 & 12345678 &  &  &  &  & \\ \hline
4 & 12345678 &  &  &  &  & \\ \hline
\end{longtable}
#+end_src


#+begin_src 

And this does not compile for TL2023, it gives the following error:
Overfull \hbox (64.42285pt too wide) in alignment at lines 28--32
 [] [] [] [] [] [] [] 
./problem.tex:34: Misplaced \noalign.
\hline ->\noalign 
                  {\ifnum 0=`}\fi \penalty \@M \futurelet \@let@token \LT@@h...l.34 \hline
           
./problem.tex:35: Misplaced \omit.
\multispan ->\omit 
                   \@multispan 
l.35 
     
./problem.tex:38: Misplaced \noalign.
\hline ->\noalign 
                  {\ifnum 0=`}\fi \penalty \@M \futurelet \@let@token \LT@@h...l.38 \hline
           
./problem.tex:39: Misplaced \omit.
\multispan ->\omit 
                   \@multispan 
l.39 \endhead
#+end_src
             


The problem are the lines \hline[0pt]

I can query replace them, but is there any other solution.

Regards

Uwe Brauer 
-- 
I strongly condemn Hamas heinous despicable pogroms/atrocities on Israel
I strongly condemn Putin's war of aggression against Ukraine.
I support to deliver weapons to Ukraine's military. 
I support the EU and NATO membership of Ukraine.