U+21B3 UTF8 character failure with \newunicodechar

the following

% file testbismon.tex
%% see https://github.com/bstarynk/bismon/ for more about Bismon
\documentclass[11pt,a4paper,svgnames]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8x]{inputenc}
\usepackage{alltt}
% https://tex.stackexchange.com/a/342804/42406
%\usepackage{textcomp}
\usepackage{moreverb}
\usepackage{fancyvrb}
\usepackage{fancyhdr}
\usepackage{fancybox}
\usepackage{epsfig}
\usepackage{makeidx}
\usepackage{float}
\usepackage{xcolor}
\usepackage{hyperref}
\usepackage{moreverb}
\usepackage{multirow}
\usepackage{boxedminipage}
\usepackage[square]{natbib}
\usepackage{charter}
%\usepackage{inconsolata}
\usepackage{listings}
\usepackage{relsize}
\usepackage{verbatimbox}
\usepackage{filecontents}
\usepackage{catchfile}
\usepackage{lastpage}
\usepackage{stmaryrd}
\usepackage{ucs}
\usepackage{stix}
\usepackage{newunicodechar}
% bigfoot enables \verb in footnotes
\usepackage{bigfoot}
\usepackage[a4paper, margin=2cm]{geometry}

\newcommand{\bmemail}[1]{{\href{mailto:#1}{\texttt{\textbf{#1}}}}}
\newcommand{\bmurl}[1]{{\href{#1}{\texttt{\textbf{#1}}}}}

% https://ctan.math.illinois.edu/macros/latex/contrib/newunicodechar/newunicodechar.pdf
% and https://tex.stackexchange.com/a/238135/42406
\newunicodechar{↳}{\rotatebox[origin=c]{180}{$\Lsh$}}

\begin{document}
\section{the test}
\begin{alltt}
the U+21B3 character is {\large ↳} \textit{DOWNWARDS ARROW WITH TIP RIGHTWARDS}
\end{alltt}
\end{document}


does not work on my Debian/Sid machine since pdflatex testbismon.tex gets the following error:

...
(/usr/share/texlive/texmf-dist/tex/latex/ucs/data/uni-33.def)
(/usr/share/texlive/texmf-dist/tex/latex/ucs/data/uninames.dat)
(/usr/share/texlive/texmf-dist/tex/latex/ucs/data/uni-33.def)

! Package ucs Error: Unknown Unicode character 8627 = U+21B3,
(ucs)                possibly declared in uni-33.def.
(ucs)                Type H to see if it is available with options.

See the ucs package documentation for explanation.
Type  H <return>  for immediate help.
...

l.50 the U+21B3 character is {\large ↳
} \textit{DOWNWARDS ARROW WITH TIP R...

?


Why does that error happens? How to get rid of it?

My above LaTeX code was inspired by this answer. I am using:

 pdfTeX 3.14159265-2.6-1.40.20 (TeX Live 2019/Debian)
kpathsea version 6.3.1


and typing my LaTeX files using emacs 26.

• newunicodechar requires not to use utf8x. Change the option to utf8 (or remove the call to inputenc altogether). Also remove \usepackage{ucs}. – egreg Jul 22 '19 at 14:18

You also get

Package newunicodechar Warning: This package only works if the document
(newunicodechar)                encoding is utf8'.


Remove \usepackage[utf8x]{inputenc} and \usepackage{ucs}.

Unrelated, but important: hyperref should be the last in your long list of packages. Also using charter and stix is a contradiction, remove the former. I wouldn't load stmaryrd along with stix. And epsfig is not to be used in newer documents: just use graphicx and its facilities.

• Should I replace \usepackage[utf8x]{inputenc} by something else, or should it be entirely removed? – Basile Starynkevitch Jul 22 '19 at 17:35
• @BasileStarynkevitch With TeX Live 2018 or later, \usepackage[utf8]{inputenc} is implied, so you don't need it. – egreg Jul 22 '19 at 17:43
• "epsfig not to be used in newer documents" where "newer" means, anything written after 1994:-) – David Carlisle Jul 22 '19 at 17:47
• I will try that at work in a few hours, it should work, and then I'll accept the answer. A big thanks, I am struggling with such issues since two weeks – Basile Starynkevitch Jul 23 '19 at 4:19
• BTW, except from experience, how do you know that charter and stix` are incompatible packages? Is there anywhere a web page saying that? I am still a bit of LaTeX newbie... (my greatest professional mistake in my life was to not writing my PhD, in 1990, using LaTeX. At that time a LaTeX distro filled the half of the disk of the Sun4/160 workstation I worked on) – Basile Starynkevitch Jul 23 '19 at 4:21