[Answered ]-Cleaned_data not working in django 1.8.6

You have defined your admin class wrong, so it is not using your custom form. You don’t use a class Meta inside a modeladmin; you just define the class attribute directly.

class SignUpAdmin(admin.ModelAdmin):
    list_display = ['full_name', 'email', 'timestamp', 'updated']
    form = SignUpForm