diff -r d427a6db1902 -r 22b5739772d8 server/python/django2/renkanmanager/serializers.py
--- a/server/python/django2/renkanmanager/serializers.py	Wed Jun 22 01:03:58 2016 +0200
+++ b/server/python/django2/renkanmanager/serializers.py	Wed Jun 22 01:15:52 2016 +0200
@@ -20,7 +20,7 @@
     revision_count = serializers.ReadOnlyField()
     created_by = serializers.SlugRelatedField(source="creator", slug_field=RENKAN_USER_DISPLAY_FIELD, read_only=True)
     last_updated_by = serializers.SerializerMethodField("get_current_revision_last_updator")
-    title = serializers.CharField(required=False)
+    title = serializers.CharField(required=False, allow_blank=True)
     content = serializers.JSONField(required=False)
     creation_date = serializers.ReadOnlyField()
     modification_date = serializers.SerializerMethodField()
@@ -67,7 +67,6 @@
         """
             Method to update a Renkan object. Creates a new revision if needed
         """
-        logger.debug('RENKAN SERIALIZER UPDATE %r', validated_data)
         updator = validated_data.get('updator')
         create_new_revision = validated_data.get("create_new_revision", False)
         title = validated_data.get('title', renkan.current_revision.title)