diff --git a/lib/xos-config/xosconfig/config.py b/lib/xos-config/xosconfig/config.py
index ff221a9..ba8e75d 100644
--- a/lib/xos-config/xosconfig/config.py
+++ b/lib/xos-config/xosconfig/config.py
@@ -136,7 +136,11 @@
         try:
             Config.validate_config_format(config_file, config_schema)
         except Exception, e:
-            raise Exception('[XOS-Config] The config format is wrong: %s' % e.msg)
+            try:
+                error_msg = e.msg
+            except AttributeError:
+                error_msg = str(e)
+            raise Exception('[XOS-Config] The config format is wrong: %s' % error_msg)
 
         with open(config_file, 'r') as stream:
             return yaml.safe_load(stream)
diff --git a/lib/xos-config/xosconfig/synchronizer-config-schema.yaml b/lib/xos-config/xosconfig/synchronizer-config-schema.yaml
index 252ccee..276268d 100644
--- a/lib/xos-config/xosconfig/synchronizer-config-schema.yaml
+++ b/lib/xos-config/xosconfig/synchronizer-config-schema.yaml
@@ -21,6 +21,10 @@
     type: str
   logging: 
     type: any
+  wrappers:
+    type: seq
+    sequence:
+    - type: str
   blueprints:
     type: seq
     sequence: