*** (job aborted, no legal \end found) error in LaTex - latex

Question

I'm having an issue with LaTex.
I'm using Overleaf to ellaborate my thesis document, and when I try to compile it, I get this error:
<*> Preambulo.tex
*** (job aborted, no legal \end found)
I've seen other questions related to this issue, but none of them was helpful. The error seems to be in my Preambulo.tex file, which is a preamble that is supposed to include all the document settings. This is what my Preambulo.tex file looks like:
\documentclass[a4paper,11pt]{book}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[english,spanish,es-lcroman]{babel}
\usepackage{bookman}
\decimalpoint
\usepackage{graphicx}
\usepackage{amsfonts,amsgen,amsmath,amssymb}
\usepackage[top=3cm, bottom=3cm, right=2.54cm, left=2.54cm]{geometry}
\usepackage{afterpage}
\usepackage{colortbl,longtable}
\usepackage[pdfborder={0 0 0}]{hyperref}
\usepackage{pdfpages}
\usepackage{url}
\usepackage[stable]{footmisc}
\usepackage{parskip} % para separar párrafos con espacio.
\usepackage{hyperref}
%%-----------------------------------------------
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhf{}
\fancyhead[LO]{\leftmark}
\fancyhead[RE]{\rightmark}
\setlength{\headheight}{1.5\headheight}
\cfoot{\thepage}
\addto\captionsspanish{ \renewcommand{\contentsname}
{Tabla de contenidos} }
\setcounter{tocdepth}{4}
\setcounter{secnumdepth}{4}
\renewcommand{\chaptermark}[1]{\markboth{\textbf{#1}}{}}
\renewcommand{\sectionmark}[1]{\markright{\textbf{\thesection. #1}}}
\newcommand{\HRule}{\rule{\linewidth}{0.5mm}}
\newcommand{\bigrule}{\titlerule[0.5mm]}
\usepackage{appendix}
\renewcommand{\appendixname}{Anexos}
\renewcommand{\appendixtocname}{Anexos}
%\renewcommand{\appendixpagename}{Anexos}
%%-----------------------------------------------
%% Páginas en blanco sin cabecera:
%%-----------------------------------------------
\usepackage{dcolumn}
\newcolumntype{.}{D{.}{\esperiod}{-1}}
\makeatletter
\addto\shorthandsspanish{\let\esperiod\es#period#code}
\def\clearpage{
\ifvmode
\ifnum \#dbltopnum =\m#ne
\ifdim \pagetotal <\topskip
\hbox{}
\fi
\fi
\fi
\newpage
\thispagestyle{empty}
\write\m#ne{}
\vbox{}
\penalty -\#Mi
}
\makeatother
%%-----------------------------------------------
%% Estilos código de lenguajes: Consola, C, C++ y Python
%%-----------------------------------------------
\usepackage{color}
\definecolor{gray97}{gray}{.97}
\definecolor{gray75}{gray}{.75}
\definecolor{gray45}{gray}{.45}
\usepackage{listings}
\lstset{ frame=Ltb,
framerule=0pt,
aboveskip=0.5cm,
framextopmargin=3pt,
framexbottommargin=3pt,
framexleftmargin=0.4cm,
framesep=0pt,
rulesep=.4pt,
backgroundcolor=\color{gray97},
rulesepcolor=\color{black},
%
stringstyle=\ttfamily,
showstringspaces = false,
basicstyle=\scriptsize\ttfamily,
commentstyle=\color{gray45},
keywordstyle=\bfseries,
%
numbers=left,
numbersep=6pt,
numberstyle=\tiny,
numberfirstline = false,
breaklines=true,
}
\lstnewenvironment{listing}[1][]
{\lstset{#1}\pagebreak[0]}{\pagebreak[0]}
\lstdefinestyle{consola}
{basicstyle=\scriptsize\bf\ttfamily,
backgroundcolor=\color{gray75},
}
\lstdefinestyle{CodigoC}
{basicstyle=\scriptsize,
frame=single,
language=C,
numbers=left
}
\lstdefinestyle{CodigoC++}
{basicstyle=\small,
frame=single,
backgroundcolor=\color{gray75},
language=C++,
numbers=left
}
\lstdefinestyle{Python}
{language=Python,
}
\makeatother
Does anyone know how to fix this issue? Thank you very much in advance.

Answer 1

For anyone interested on this problem, the issue seems to be that the main file selected in my overleaf project was wrong: it was Preamble.tex instead of main.tex
I went to the menu in the upper left corner of the page and changed the main file to main.tex. Now it works fine.

Answer 2

I received the same error because I was trying to compile my settings.tex file (which similarly lists all my document settings) instead of compiling my main.tex file. Make sure you are compiling the correct document.