Adapted Code for Django 1.11 and Python 3,

updated the CKEditor

src/content/models.py

@@ -77,7 +77,7 @@ class Article(models.Model):
         self.content_de = cleaner.clean_html(self.content_de)
         self.content_en = cleaner.clean_html(self.content_en)
 
-    def __unicode__(self):
+    def __str__(self):
         return self.headline
 
     @property
@@ -199,7 +199,7 @@ class Page(models.Model):
         verbose_name=_('latest updated at'),
     )
 
-    def __unicode__(self):
+    def __str__(self):
         return u'%s' % self.title
 
     @property
@@ -291,7 +291,7 @@ class Category(models.Model):
     def get_absolute_url(self):
         return reverse('article-archive', kwargs={'category': self.slug})
 
-    def __unicode__(self):
+    def __str__(self):
         return self.name