Hi Henri,
This file works well with context but does not work with lmtx.

\usemodule[pgfplots]
\usemodule[pgfpltstable]
\pgfplotsset{compat=newest}
\starttext
\starttikzpicture
\startaxis[
    title={\bf Relevé de notes chronologique},
    ymajorgrids=true,
    grid style={cyan!30},
    ymin=0,
    ymax=22,
    xmin=0,
    xmax=14,
    x=1cm,
    y=0.3cm,
    axis x line =bottom,
    axis y line =left,
    axis on top=true,
    axis line style =very thick,
    tick align=outside,
    tickwidth=0.12cm,
    tick style=very thick,
    xtick={\empty},
    ytick={0,2,...,18,20},
    extra x ticks={2,5,7,9,11,13},
    extra x tick labels={octobre,novembre,janvier,mars,avril, juin},
    extra x tick style={tick label style={rotate=45}},
    extra tick style={tick style={draw=none}},
    xlabel={Date},ylabel={Note},
    xlabel={Date},ylabel={Effectif},
 every axis x label/.style={
 at={(ticklabel* cs:1.01)},
 anchor=west,
 },
 every axis y label/.style={
 at={(ticklabel* cs:1.01)},
 anchor=south,
 },
 samples=1000,
 >=stealth,
]
\addplot [color=green,only marks] coordinates {
  (1,5)
  (2,7)
  (3,5)
  (4,10)
  (5,5)
  (6,8)
  (7,10)
  (8,8)
  (9,10)
  (10,14)
  (11,18)
  (12,14)
  (13,11)
};
\stopaxis
\stoptikzpicture
\stoptext


open source     > level 7, order 88, name 'pgfplotsbinary.data.code.tex'

tex error       > tex error on line 5 in file pgfplotsbinary.data.code.tex:
! Undefined control sequence

l.5 ...ode`\^0=11    \expandafter\xdef\csname pgfp@bin@\the\counter
\endcsname{^0

    }\advance\counter by1
lua error:

?



<empty file>


The control sequence at the end of the top line of your error message was
never
\def'ed. You can just continue as I'll forget about whatever was undefined.


mtx-context     | fatal error: return code: 256

TeX Output exited abnormally with code 1 at Wed Apr  8 11:49:56


Le mer. 8 avr. 2020 à 11:21, Henri Menke <henrimenke@gmail.com> a écrit :

> Hi Fabrice,
>
> Could you provide a MWE, or maybe even open an issue on the bugtracker?
> https://github.com/pgf-tikz/pgfplots/issues
>
> Cheers, Henri
>
> On 07/04/20, 14:22, Fabrice Couvreur wrote:
> > Hi Henri,
> > Thank you for answering me. We're entering an area that I don't really
> know. I
> > replaced all ^^ by ^ but I'm not sure I understood. I now have the
> > following message :
> > Thank you
> > Fabrice
> >
> > tex error       > tex error on line 5 in file
> pgfplotsbinary.data.code.tex:
> > ! Undefined control sequence
> >
> > l.5 \catcode`\^00=11 \expandafter\xdef\csname pgfp@bin@\the\counter
> > \endcsname{^0
> >
> >    0}\advance\counter by1
> > lua error:
> >
> > ?
> >
> >
> >
> > <empty file>
> >
> >
> > The control sequence at the end of the top line of your error message was
> > never
> > \def'ed. You can just continue as I'll forget about whatever was
> undefined.
> >
> >
> > mtx-context     | fatal error: return code: 256
> >
> > TeX Output exited abnormally with code 1 at Tue Apr  7 14:15:58
> >
> > Le mar. 7 avr. 2020 à 04:21, Henri Menke <henrimenke@gmail.com> a écrit
> :
> >
> > > The problem is that pgfplots uses the ^^ syntax to access characters
> but
> > > this relies on ^ having catcode 7 which is not the case by default in
> > > ConTeXt.  I had a similar issue in PGF before and that was fixed by
> just
> > > replacing the ^^ syntax with the ascii code constants from
> > > syst-ini.mkxl.
> > >
> > > Cheers, Henri
> > >
> > > On 06/04/20, 22:23, Fabrice Couvreur wrote:
> > > > Hi,
> > > > Still with the idea of using lmtx, I get a compilation error when I
> use
> > > > pgfplots.
> > > > Thank you.
> > > > Fabrice
> > > > ####################################################
> > > > open source     > level 9, order 92, name
> 'pgfplotsbinary.data.code.tex'
> > > >
> > > > tex error       > tex error on line 42 in file
> > > > pgfplotsbinary.data.code.tex: ! Undefined control sequence
> > > >
> > > > l.42 \catcode`\ =11^^I\expandafter\xdef\csname pgfp@bin@
> > > >
> > > > \the\counter^^I\endcsname{^^20}\endgroup\advance\counter by1
> > > > lua error:
> > > >
> > > > ?
> > > >
> > > >
> > > >
> > > > <empty file>
> > > >
> > > >
> > > > The control sequence at the end of the top line of your error
> message was
> > > > never
> > > > \def'ed. You can just continue as I'll forget about whatever was
> > > undefined.
> > > >
> > > >
> > > > mtx-context     | fatal error: return code: 256
> > > >
> > > > TeX Output exited abnormally with code 1 at Mon Apr  6 22:19:01
> > >
> > > >
> > >
> ___________________________________________________________________________________
> > > > If your question is of interest to others as well, please add an
> entry
> > > to the Wiki!
> > > >
> > > > maillist : ntg-context@ntg.nl /
> > > http://www.ntg.nl/mailman/listinfo/ntg-context
> > > > webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
> > > > archive  : https://bitbucket.org/phg/context-mirror/commits/
> > > > wiki     : http://contextgarden.net
> > > >
> > >
> ___________________________________________________________________________________
> > >
> > >
> > >
> ___________________________________________________________________________________
> > > If your question is of interest to others as well, please add an entry
> to
> > > the Wiki!
> > >
> > > maillist : ntg-context@ntg.nl /
> > > http://www.ntg.nl/mailman/listinfo/ntg-context
> > > webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
> > > archive  : https://bitbucket.org/phg/context-mirror/commits/
> > > wiki     : http://contextgarden.net
> > >
> > >
> ___________________________________________________________________________________
> > >
>
> >
> ___________________________________________________________________________________
> > If your question is of interest to others as well, please add an entry
> to the Wiki!
> >
> > maillist : ntg-context@ntg.nl /
> http://www.ntg.nl/mailman/listinfo/ntg-context
> > webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
> > archive  : https://bitbucket.org/phg/context-mirror/commits/
> > wiki     : http://contextgarden.net
> >
> ___________________________________________________________________________________
>
>
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to
> the Wiki!
>
> maillist : ntg-context@ntg.nl /
> http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
> archive  : https://bitbucket.org/phg/context-mirror/commits/
> wiki     : http://contextgarden.net
>
> ___________________________________________________________________________________
>