The rules applicable to internships were amended during the year 2014, by Law N° 2014-788 and Decree N° 2014-1420.  

Internship agreements concluded since 1 December 2014 must include new mandatory references. In effect, the Ministry of Education published in the Official Journal of 10 February 2015, a new internship agreement template as well as the internship certification to be issued by companies.
Moreover, the welcoming body must provide to the intern a certification specifying the term of the internship and the amount of a stipend, if applicable.

Links:

http://legifrance.gouv.fr/affichTexte.do;jsessionid=?cidTexte=JORFTEXT000030212676&dateTexte=&oldAction=dernierJO&categorieLien=id