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I am using chemnum package and since last updates of l3packages, l3kernel and l3experimental when I compile my code there are 14 errors. The first one is:

LaTeX error: "kernel/command-not-defined"

Control sequence \chemnum_aux_file undefined

Despite this error the code is working and it gives me a good output, but this error should mean something:

\documentclass[a4paper, 10pt]{report} %environnement du document
\usepackage[T1]{fontenc} %prise en charge des caractères spéciaux
\usepackage[frenchb]{babel} %langue
\usepackage{graphicx} %prise en charge des graphiques eps
\geometry{margin=55pt} %marges
\usepackage{indentfirst} %indentation après le titre de section
\usepackage[bottom]{footmisc} %bas de page en toute fin de page
\usepackage{csquotes} %pour la biblio
\usepackage[backend=biber,style=chem-acs,subentry,maxnames=20]{biblatex} %style acs
\usepackage{chemnum,chemstyle,chemscheme}%pour les schémas de chimie

\usepackage[version=3]{mhchem}  %prise en charge de l'écriture chimique


\begin{scheme}[H] %le H permet de fixer l'image ici
        \label{13} %permet de faire reference dans le texte


Is there a way to fix it?

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A number of things appear to have been broken by recent updates to l3kernel and l3packages. For example, I (and others) are finding that unicode-math no longer works as it should. – Evan Cooch Jul 25 '12 at 15:10
up vote 4 down vote accepted

I already fixed that and sent an update to CTAN. Version 0.5c is already available there.

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Ok, I will update teh package – Thomas C Jul 25 '12 at 15:27
@cgnider Could I check exactly what broke: we did try to avoid any issues, so I wonder which change in the code caused this. – Joseph Wright Jul 25 '12 at 16:15
@JosephWright chemnum writes the compound numbers to an aux file \chemnum_aux_file: and chemnum was missing a \iow_new:N \chemnum_aux_file: so this was rather a bug in chemnum, I guess. – clemens Jul 25 '12 at 16:21
@JosephWright in another of my packages I had troubles, though, as it was relying on xparse's (now missing) \NoValue to fool some commands to be fed with no value instead of an empty one. I fixed that, too, and probably should have designed the function using it differently in the first place, so ... – clemens Jul 25 '12 at 16:27
@cgnieder On the first point: OK, that was one of the 'breaking' changes we knew about. On the second point: Part of the reason for the change was that having \NoValue 'accessible' was asking for trouble, as there was the danger of people doing \foo[\NoValue] which was never the intention. So again this is 'to be expected'. I assume you are on LaTeX-L if only to pick up my announcements? – Joseph Wright Jul 25 '12 at 16:32

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