# LaTeX Error: \begin{paracol}

I've downloaded the latex template of MDPI and I am able to work with the LaTeX template.

%  LaTeX support: latex@mdpi.com
%  For support, please attach all files needed for compiling as well as the log file, and specify your operating system, LaTeX version, and LaTeX editor.

%=================================================================
\documentclass[journal,article,submit,moreauthors,pdftex]{Definitions/mdpi}

\firstpage{1}
\makeatletter
\setcounter{page}{\@firstpage}
\makeatother
\pubvolume{1}
\issuenum{1}
\articlenumber{0}
\pubyear{2021}
\dateaccepted{}
\datepublished{}
\hreflink{https://doi.org/} % If needed use \linebreak

\Title{Title}

% MDPI internal command: Title for citation in the left column
\TitleCitation{Title}

% Author Orchid ID: enter ID or remove command
\newcommand{\orcidauthorA}{0000-0000-0000-000X} % Add \orcidA{} behind the author's name
%\newcommand{\orcidauthorB}{0000-0000-0000-000X} % Add \orcidB{} behind the author's name

% Authors, for the paper (add full first names)
\Author{Firstname Lastname $^{1,\dagger,\ddagger}$\orcidA{}, Firstname Lastname $^{1,\ddagger}$ and Firstname Lastname $^{2,}$*}

% MDPI internal command: Authors, for metadata in PDF
\AuthorNames{Firstname Lastname, Firstname Lastname and Firstname Lastname}

% MDPI internal command: Authors, for citation in the left column
\AuthorCitation{Lastname, F.; Lastname, F.; Lastname, F.}
% If this is a Chicago style journal: Lastname, Firstname, Firstname Lastname, and Firstname Lastname.

$^{1}$ \quad Affiliation 1; e-mail@e-mail.com\\
$^{2}$ \quad Affiliation 2; e-mail@e-mail.com}

% Contact information of the corresponding author
\corres{Correspondence: e-mail@e-mail.com; Tel.: (optional; include country code; if there are multiple corresponding authors, add author initials) +xx-xxxx-xxx-xxxx (F.L.)}

% Current address and/or shared authorship
\secondnote{These authors contributed equally to this work.}
% The commands \thirdnote{} till \eighthnote{} are available for further notes

%\simplesumm{} % Simple summary

%\conference{} % An extended version of a conference paper

% Abstract (Do not insert blank lines, i.e. \\)
\abstract{A single paragraph of about 200 words maximum. For research articles, abstracts should give a pertinent overview of the work. We strongly encourage authors to use the following style of structured abstracts, but without headings: (1) Background: place the question addressed in a broad context and highlight the purpose of the study; (2) Methods: describe briefly the main methods or treatments applied; (3) Results: summarize the article's main findings; (4) Conclusion: indicate the main conclusions or interpretations.}

% Keywords
\keyword{keyword 1; keyword 2; keyword 3 (List three to ten pertinent keywords specific to the article; yet reasonably common within the subject discipline.)}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\begin{document}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Introduction}

The introduction should briefly place the study in a broad context and highlight why it is important. As far as possible, please keep the introduction comprehensible to scientists outside your particular field of research. Citing a journal paper \cite{ref-journal}.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Materials and Methods}

Materials and Methods should be described with sufficient details to allow others to replicate and build on published results.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Results}

This section may be divided by subheadings. It should provide a concise and precise description of the experimental results, their interpretation as well as the experimental conclusions that can be drawn.
\subsection{Figures, Tables and Schemes}

All figures and tables should be cited in the main text as Figure~\ref{fig1}, Table~\ref{tab1}, etc.

\begin{figure}[H]
\includegraphics[width=10.5 cm]{Definitions/logo-mdpi}
\caption{This is a figure. Schemes follow the same formatting. If there are multiple panels, they should be listed as: (\textbf{a}) Description of what is contained in the first panel. (\textbf{b}) Description of what is contained in the second panel. Figures should be placed in the main text near to the first time they are cited. A caption on a single line should be centered.\label{fig1}}
\end{figure}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Discussion}

Authors should discuss the results and how they can be interpreted from the perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible. Future research directions may also be highlighted.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Conclusions}

This section is not mandatory, but can be added to the manuscript if the discussion is unusually long or complex.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\end{paracol}
\reftitle{References}

\begin{thebibliography}{999}
% Reference 1
\bibitem[Author1(year)]{ref-journal}
Author~1, T. The title of the cited article. {\em Journal Abbreviation} {\bf 2008}, {\em 10}, 142--149.
\end{thebibliography}
\end{document}

The only problem is when I delete `\end{paracol}, I faced the following error

LaTeX Error: \begin{paracol} on input line 65 ended by \end{document}.

Notice: I used the overleaf in link mdpi.com/authors/latex

• You should probably provide a link to the files for this template as it uses stuff we do not have access to. May 21, 2021 at 7:18
• I don't see a \begin{paracol} in your code, so this must be in one of the other files. May 21, 2021 at 7:33
• I used the overleaf in link mdpi.com/authors/latex May 21, 2021 at 7:33
• @Pieter van Oostrum I tried to put \begin{paracol} in beginning but it's not working! I don't know where should I put it? May 21, 2021 at 7:36

UPDATE: I contacted MDPI about this, and the template is supposed to be as it is. You should not delete the \end{paracol} in your document; it ends the \begin{paracol} in the class file, and that is how it is supposed to be. The whole document, except the references is in two columns, a narrow one for notes, references and the like, and a wide of tor the actual article text.

There is a \begin{paracol} in mdpi.cls in \newcommand{\maketitlen}{... but no \end{paracol}. If you add this at the end of the command, it will work. Here are the relevant lines:

\end{spacing}
\end{flushleft}
}
}

%%%% Abstract, keywords, journal data, PACS, MSC, JEL
\newcommand{\abstractkeywords}{
• That seems to be ground for a bug report May 21, 2021 at 7:55
• @Pieter van Oostrum thank you, should i delete \end{paracol} in my paper template? May 21, 2021 at 7:57
• Yes, because there is no corresponding \begin{paracol} in your paper. May 21, 2021 at 8:06
• I have reported it to latex@mdpi.com. May 21, 2021 at 8:11
• I got their response, and it is supposed to be like it is now. So you should not delete the \end{paracol}. See my update. May 24, 2021 at 8:18

the \end{paracol} command must be just before wide figures, and before bibliography

For me this one worked when using Overleaf:

Add this command on line 232

%%begin novalidate % <----- Add this command
\end{paracol}
%%end novalidate % <----- Add this command

This command hides the warnings on Overleaf.

Source 2 and explanation: https://issueexplorer.com/issue/lervag/vimtex/2171

• This is the simplest, non-invasive method. And the whole manuscript is not highlighted in red finally! (I've tried hacking the .cls file, and there were problems or timeouts; besides---will the hacked source be OK for submission?) Nov 18, 2021 at 14:36

I tried @Pieter's solution, but I still had some unformatting issues in the Abstract and Keywords sections.

Similarly to what @Pieter suggested, I solved by adding a \end{paracol} in the mdpi.cls as follows:

%%%% Print maketitle and abstractkeywords
\ifthenelse{\equal{\@arttype}{Supfile}}{
\AfterEndPreamble{
\maketitle
\let\maketitle\relax
\columnratio{0.23} % (textwidth 18.53 cm + margins 2x1.27 = 21.07 = A4) 4.6 cm indent is 1/4 of the textwidth
\begin{paracol}{2}
\switchcolumn
\ifthenelse{\equal{\@status}{submit}}{\linenumbers}{}
}%
}{
\AfterEndPreamble{
\maketitle
\let\maketitle\relax
\maketitlen
\let\maketitlen\relax
\ifthenelse{\equal{\@status}{submit}}{\linenumbers}{}
\abstractkeywords
\end{paracol} % <----- Add this command here
}%
}
\AtBeginDocument{
\DeclareSymbolFont{AMSb}{U}{msb}{m}{n}
\DeclareSymbolFontAlphabet{\mathbb}{AMSb}
}

Then, to make the template work in two columns, I added the following right after the \begin{document}.

\begin{document}
\begin{paracol}{2} <--- Add begin new paracol
\switchcolumn      <--- Go to right column