diff --git a/sat/plugins/plugin_xep_0231.py b/sat/plugins/plugin_xep_0231.py
index e21c4bc7..ec55b502 100644
--- a/sat/plugins/plugin_xep_0231.py
+++ b/sat/plugins/plugin_xep_0231.py
@@ -184,11 +184,12 @@ class XEP_0231(object):
             client.send(error_elt)
             return
 
-        with open(metadata["path"]) as f:
+        with open(metadata["path"], 'rb') as f:
             data = f.read()
 
         result_elt = xmlstream.toResponse(iq_elt, "result")
-        data_elt = result_elt.addElement((NS_BOB, "data"), content=data.encode("base64"))
+        data_elt = result_elt.addElement(
+            (NS_BOB, "data"), content=base64.b64encode(data).decode())
         data_elt["cid"] = cid
         data_elt["type"] = metadata["mime_type"]
         data_elt["max-age"] = str(int(max(0, metadata["eol"] - time.time())))
@@ -198,7 +199,9 @@ class XEP_0231(object):
         peer_jid = jid.JID(peer_jid_s)
         assert cid
         client = self.host.getClient(profile)
-        return self.getFile(client, peer_jid, cid)
+        d = self.getFile(client, peer_jid, cid)
+        d.addCallback(lambda path: str(path))
+        return d
 
     def getFile(self, client, peer_jid, cid, parent_elt=None):
         """Retrieve a file from it's content-id
@@ -208,7 +211,7 @@ class XEP_0231(object):
         @param parent_elt(domish.Element, None): if file is not in cache,
             data will be looked after in children of this elements.
             None to ignore
-        @return D(unicode): path to cached data
+        @return D(Path): path to cached data
         """
         file_path = client.cache.getFilePath(cid)
         if file_path is not None:
diff --git a/sat/plugins/plugin_xep_0264.py b/sat/plugins/plugin_xep_0264.py
index e5ea129a..45240ff6 100644
--- a/sat/plugins/plugin_xep_0264.py
+++ b/sat/plugins/plugin_xep_0264.py
@@ -131,7 +131,7 @@ class XEP_0264(object):
         @param size(tuple(int)): requested size of thumbnail
         @return (unicode): unique id for this image/size
         """
-        return hashlib.sha256(repr((image_uid, size))).hexdigest()
+        return hashlib.sha256(repr((image_uid, size)).encode()).hexdigest()
 
     def _blockingGenThumb(self, source_path, size=None, max_age=None, image_uid=None):
         """Generate a thumbnail for image