diff -up syncevolution-1.5.3/test/syncevo-http-server.py.python3-2 syncevolution-1.5.3/test/syncevo-http-server.py
--- syncevolution-1.5.3/test/syncevo-http-server.py.python3-2	2020-05-11 12:10:50.479969706 +0200
+++ syncevolution-1.5.3/test/syncevo-http-server.py	2020-05-11 12:12:43.627963000 +0200
@@ -131,7 +131,7 @@ class SyncMLSession:
         then remove the session'''
         logger.debug("destructing connection %s with code %s message %s", self.conpath, code, message)
         if self.request:
-            self.request.setResponseCode(code, message)
+            self.request.setResponseCode(code, message.encode())
             self.request.finish()
             self.request = None
         if self.connection:
@@ -179,7 +179,7 @@ class SyncMLSession:
             OldRequest.type = type
             if request:
                 request.setHeader('Content-Type', type)
-                request.setHeader('Content-Length', len(data))
+                request.setHeader('Content-Length', str(len(data)))
                 request.setResponseCode(http.OK)
                 request.write(data)
                 request.finish()
@@ -243,7 +243,6 @@ class SyncMLSession:
                                         'org.syncevolution',
                                         self.conpath,
                                         path_keyword='conpath',
-                                        utf8_strings=True,
                                         byte_arrays=True)
         self.reply_match = \
         Context.bus.add_signal_receiver(self.reply,
@@ -252,7 +251,6 @@ class SyncMLSession:
                                         'org.syncevolution',
                                         self.conpath,
                                         path_keyword='conpath',
-                                        utf8_strings=True,
                                         byte_arrays=True)
 
         # feed new data into SyncEvolution and wait for reply
@@ -319,16 +317,16 @@ class SyncMLPost(resource.Resource):
             config = ""
         type = request.getHeader('content-type')
         len = request.getHeader('content-length')
-        sessionid = request.args.get('sessionid')
+        sessionid = request.args.get(b'sessionid')
         if sessionid:
-            sessionid = sessionid[0]
+            sessionid = sessionid[0].decode()
         logger.debug("POST from %s config %s type %s session %s args %s length %s",
                      request.getClientIP(), config, type, sessionid, request.args, len)
         if not sessionid:
             logger.info("new SyncML session for %s", request.getClientIP())
             session = SyncMLSession()
             session.start(request, config,
-                          urllib.parse.urljoin(self.url.geturl(), request.path))
+                          urllib.parse.urljoin(self.url.geturl(), request.path.decode()))
             return server.NOT_DONE_YET
         else:
             data = request.content.read()
@@ -587,7 +585,7 @@ syncevo-http-server itself is installed"
 
     url = urllib.parse.urlparse(args[0])
     root = resource.Resource()
-    root.putChild(url.path[1:], SyncMLPost(url))
+    root.putChild(url.path[1:].encode(), SyncMLPost(url))
     site = server.Site(root)
     if url.scheme == "https":
         if not options.cert: