Package etex Warning : Extended allocation already in use

Question

When I try to compile my document, I get the following warning and errors.

Here is the start of my document:

\documentclass{birkmono}
%\usepackage[round]{natbib}
%\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[french,ngerman,english]{babel}
\usepackage{amsmath}
%\usepackage{amsthm}
%\usepackage{ngerman}
\usepackage{graphicx}
\usepackage{latexsym,amssymb,amsthm}
\usepackage[backend=biber,
                    style=authoryear,
                    natbib=true,
                    giveninits=true]
                    {biblatex}
\addbibresource{Duality_Marquis.bib}
\newtheorem{definition}{Definition}
\newtheorem{theorem}{Theorem}
\newtheorem{corollary}{Corollary}
\newtheorem{lemma}{Lemma}
\usepackage{enumitem}
\usepackage{tikz-cd}
\usepackage{epigraph}
\setlength\epigraphwidth{.8\textwidth}
\theoremstyle{definition}

Is there a simple way to solve my problem?

Answer 1

You have old local copies of biblatex and etoolbox packages (see the paths shown in your image of the terminal output)

Delete them and then latex will find the standard ones distributed with texlive 2021.

More generally you should delete (or at least backup and move out of the tex input path) any packages in the /Users/marquisj/Library/texmf that mask standard packages, only put your own local packages there that are not copies of texlive files.

Answer 2

The "Extended allocation already in use" warning is probably due to the fact that according to https://tex.stackexchange.com/a/186597/52414

Recent LaTeX kernels have incorporated the greater part of etex, so it's quite unlikely that one needs to load it nowadays.

So the etex package correctly determines that it is obsolete. Perhaps future versions of etoolbox won't load that package anymore in the first place, so that warning will no longer show up. Until then I believe we can simply ignore it.