diff -r 22b5739772d8 -r 192ce5938726 server/python/django2/renkanmanager/models.py
--- a/server/python/django2/renkanmanager/models.py	Wed Jun 22 01:15:52 2016 +0200
+++ b/server/python/django2/renkanmanager/models.py	Thu Jun 23 17:50:37 2016 +0200
@@ -125,7 +125,7 @@
         return self.current_revision and self.current_revision.content or ''
 
     def __str__(self):
-        return self.renkan_guid
+        return str(self.renkan_guid)
 
     @transaction.atomic
     def save_renkan(self, updator, timestamp="", title="", content="", create_new_revision=False):