Thank you.
I have found the origin of the problem : I'm using in customized layout the following text :
{{Start Date:STARTDATE}}
to get the stardate of the record. Then I want to get the day, month number and year as dd-mm-YYYY.
I transform the text with
$date = new DateTime($parm)
where $parm is {{Start Date:STARTDATE}}.
No problem when the site is in english. When the site is in french the $parm transformation gives the error.
Is it possible to get STARDATE with only dd,mm,YYYY in the customized layout ?
thank you for advices
best regards
Michel Rottenberg