coercing to Unicode: need string or buffer, NoneType found when rendering in django admin

Question

I have this error since a long time but can\'t figure it out :

Caught TypeError while rendering: coercing to Unicode: need string or buffer, NoneType found

Answer 1

Replace the earlier function with the provided one. The simplest solution is:

def __unicode__(self):

    return unicode(self.nom_du_site)