--- a/src/twisted/plugins/libervia_server.py	Mon Jan 25 17:02:13 2016 +0100
+++ b/src/twisted/plugins/libervia_server.py	Fri Feb 12 19:32:43 2016 +0100
@@ -70,12 +70,21 @@
 
 
 def coerceConnectionType(value):  # called from Libervia.OPT_PARAMETERS
+    if isinstance(value, unicode):
+        # XXX: if value comes from sat.conf, it's unicode,
+        # and we need byte str here (for twisted)
+        value = value.encode('utf-8')
     allowed_values = ('http', 'https', 'both')
     if value not in allowed_values:
         raise ValueError("%(given)s not in %(expected)s" % {'given': value, 'expected': str(allowed_values)})
     return value
 
 def coerceDataDir(value):  # called from Libervia.OPT_PARAMETERS
+    if isinstance(value, unicode):
+        # XXX: if value comes from sat.conf, it's unicode,
+        # and we need byte str here (for twisted)
+        value = value.encode('utf-8')
+    value = value.encode('utf-8')
     html = os.path.join(value, C.HTML_DIR)
     if not os.path.isfile(os.path.join(html, C.LIBERVIA_MAIN_PAGE)):
         raise ValueError("%s is not a Libervia's browser HTML directory" % os.path.realpath(html))