Hello,
I just updated context standalone and this file does not compile anymore,
but I do not see why.
Thank you
Fabrice

\switchtobodyfont[11pt]

    \definelayout
      [noheader]
      [header=26pt,
       headerdistance=25pt,
       backspace=2cm,
       width=middle,
       topspace=\dimexpr 2cm-\headerheight-\headerdistance\relax,
       footer=16pt,
       height=middle]

    \setuplayout
      [header=\zeropoint,
       headerdistance=25pt,
       backspace=2cm,
       width=middle,
       topspace=\dimexpr 2cm-\headerheight-\headerdistance\relax,
       footer=16pt,
       height=middle]

    \definelayout[1][noheader]

    \setuppagenumbering
        [alternative=,
         location={footer,right]

    \setupbackgrounds[header][text]
                     [frame=off,
                      bottomframe=on,
                      framecolor=gray,
                      rulethickness=2pt]

    \defineframed[headerframed]
                 [frame=off,
                  location=depth,
                  bottomoffset=\lineheight,
                  align=middle,
                  width=fit]

    \setupheadertexts[\headerframed{\ss\sc\bf\red Contrôle n\high{o}\,1 \\
}]

    \setupheadertexts
            [\headerframed{\tfx\ss Lycée JANSON DE SAILLY\\ 31 juillet
2017}]
            [\headerframed{\tfx\ss T\high{le} ES 2 \\ Durée 1 heure 30}]

    \starttext
    \dorecurse{10}{\input knuth}
    \stoptext