Accents characters are hidden in beamer mode

I am trying to use a beamer template that I a user shared with me. Unfortunately, I have an issue using accents (because I write in French) : It seems like characters using accents are ignored and not shown on the template. For instance writing : "Etalement à interface élastique" gives "Etalement interface lastique"

I use this sty file : named "YTU.sty"

\mode<presentation>

\ProcessOptionsBeamer

\useoutertheme[footline=authorinstitutetitle,subsection=false]{smoothbars}
\makeatletter % [add curpage/total page at the bottom](http://tex.stackexchange.com/questions/100838/beamer-dresden-theme-miniframes-appeareance-and-frame-number-insertion)
\newcommand{\frameofframes}{/}
\setbeamertemplate{footline}
{%
\begin{beamercolorbox}[colsep=1.5pt]{upper separation line foot}
\end{beamercolorbox}
\begin{beamercolorbox}[ht=2.5ex,dp=1.125ex,%
\hfill%
\end{beamercolorbox}%
\begin{beamercolorbox}[ht=2.5ex,dp=1.125ex,%
\hfill%
\end{beamercolorbox}%
\begin{beamercolorbox}[colsep=1.5pt]{lower separation line foot}
\end{beamercolorbox}
}
\makeatother

\useinnertheme{circles}

%\useoutertheme{default}

%define qut theme color
\xdefinecolor{qut}{HTML}{00407a}  %PANTONE 541 BLUE
\setbeamercolor{footline}{bg=qut}
\setbeamercolor{frametitle}{bg=qut,fg=white}
\setbeamercolor{title}{bg=qut}
\setbeamerfont{frametitle}{size=\large}
\setbeamertemplate{bibliography item}[text]
\setbeamertemplate{caption}[numbered]

\setbeamercolor{palette primary}{use=structure,fg=white,bg=structure.fg}
\setbeamercolor{palette secondary}{use=structure,fg=white,bg=structure.fg!75!black}
\setbeamercolor{palette tertiary}{use=structure,fg=white,bg=structure.fg!50!black}
\setbeamercolor{palette quaternary}{fg=white,bg=structure.fg!50!black}
%\setbeamercolor*{sidebar}{use=structure,bg=structure.fg}
\setbeamercolor{titlelike}{parent=palette primary}

%% try
\setbeamercolor{block title}{bg=qut}
\setbeamercolor*{block title example}{use={normal text,example text},bg=white,fg=qut}
\setbeamercolor{fine separation line}{}
\setbeamercolor{item projected}{fg=white}
\setbeamercolor{palette sidebar primary}{use=normal text,fg=normal text.fg}
\setbeamercolor{palette sidebar quaternary}{use=structure,fg=structure.fg}
\setbeamercolor{palette sidebar secondary}{use=structure,fg=structure.fg}
\setbeamercolor{palette sidebar tertiary}{use=normal text,fg=normal text.fg}
%\setbeamercolor{palette sidebar quaternary}{fg=white}
\setbeamercolor{section in sidebar}{fg=brown}
\setbeamercolor{separation line}{}
\setbeamercolor{sidebar}{bg=qut}
\setbeamercolor{sidebar}{parent=palette primary}
\setbeamercolor{structure}{fg=qut}
\setbeamercolor{subsection in sidebar}{fg=brown}
\AtBeginSection[]{
\begin{frame}
\end{frame}
}
\AtBeginSubsection[]{
\begin{frame}
\end{frame}
}

\mode
<all>

This is the code of the template :

% !TEX encoding = UTF-8 Unicode
\documentclass[french]{beamer}
\usepackage{hyperref}
\usepackage[utf8]{inputenc}

%\usepackage[T1]{fontenc}
\UseRawInputEncoding

\usepackage{pgfpages}

\usetikzlibrary{arrows.meta,
patterns.meta
}

% other packages
\usepackage{latexsym,amsmath,xcolor,multicol,booktabs,calligra}
\usepackage{graphicx,listings,stackengine}

%% Enable only in Xelatex
% \usepackage{pstricks}

\author{XXX}
\title{Etalement d'une goutte à interface élastique}
\subtitle{Presentation}
\institute [Sorbonne Université - ESPCI, Paris] {Laboratoire PMMH \\PSL University}
\date{\today}

\usepackage{YTU}

% defs
\def\cmd#1{\texttt{\color{red}\footnotesize $\backslash$#1}}
\def\env#1{\texttt{\color{blue}\footnotesize #1}}
\definecolor{deepblue}{rgb}{0,0,0.5}
\definecolor{deepred}{rgb}{0.6,0,0}
\definecolor{deepgreen}{rgb}{0,0.5,0}
\definecolor{halfgray}{gray}{0.55}

\lstset{
basicstyle=\ttfamily\small,
keywordstyle=\bfseries\color{deepblue},
emphstyle=\ttfamily\color{deepred},    % Custom highlighting style
stringstyle=\color{deepgreen},
numbers=left,
numberstyle=\small\color{halfgray},
rulesepcolor=\color{red!20!green!20!blue!20},
}

\begin{document}

\begin{frame}
\titlepage

\begin{note}
\end{note}

\end{frame}
\end{document}

Could someone help me to solve this problem please ?

• What should be the purpose of \UseRawInputEncoding? Sep 12 at 9:55
• While testing the original template it was told to me that is used to display the code but to be honest I don't understand its use very well. Does it interfere with utf8 encoding ? I have tried to remove it and now it works well...
– Wiss
Sep 12 at 9:59
• @egreg Thank you for your remark but do you know what is the reason behind this error ? Thanks
– Wiss
Sep 12 at 10:00
• Unrelated to the problem, but your preamble could do with a clean up: lot's of unnecessary packages... Sep 12 at 10:04

Remove \UseRawInputEncoding, that's all.

If you look in the .log file, you will see

Missing character: There is no <C3> in font cmss8!
Missing character: There is no <A9> in font cmss8!
Missing character: There is no <C3> in font cmss8!
Missing character: There is no <A0> in font cmss8!
Missing character: There is no <C3> in font cmss8!
Missing character: There is no <A9> in font cmss8!
Missing character: There is no <C3> in font cmss12!
Missing character: There is no <A0> in font cmss12!
Missing character: There is no <C3> in font cmss12!
Missing character: There is no <A9> in font cmss12!
Missing character: There is no <C3> in font cmss8!
Missing character: There is no <A9> in font cmss8!
Missing character: There is no <C3> in font cmss8!
Missing character: There is no <A0> in font cmss8!
Missing character: There is no <C3> in font cmss8!
Missing character: There is no <A9> in font cmss8!

The precise purpose of \UseRawInputEncoding is to absorb the input byte by byte without assuming any encoding; since the main document font (Computer Modern Sans) has nothing in the 128–255 slots, that's what happens. With a different font you might get arbitrary rubbish.

Removing that wrong declaration yields

Since you're writing in French you should also reenable \usepackage[T1]{fontenc} and add \usepackage{babel}.

Isn't the correct French spelling “Étalement”? I don't think you should omit accents on uppercase letters.