TeX - ! Extra alignment tab has been changed to \cr

[David Carlisle]

http://tug.org/mail-archives/texhax/2019-July/023762.html

You don't actually post a test document there but if I complete it to
a document that makes the error

\documentclass{article}

\begin{document}

\begin{tabular}{cccc}
\hbox to 2cm {una} & prueba && \cr
para ver &&&& \cr} & & & &      % look at the closing brace and hence the
missing \cr.
\end{tabular}

\end{document}


Then despite the comment the error is raised before tex has seen
mismatched brace as the error shows

! Extra alignment tab has been changed to \cr.
<recently read> \endtemplate

l.7 para ver &&&&
                  \cr} & & & &      % look at the closing brace and hence the

where the linebreak show how far tex has read.

the error is simply telling you that you have 4 & in  a table that has
4 columns so that only three & are allowed.

So it is the same as this example using standard latex syntax



\documentclass{article}

\begin{document}

\begin{tabular}{cccc}
una & prueba && \\
para ver &&&&
\end{tabular}

\end{document}


so you get an error message as there is a user error in the file.