diff --git a/product/ERP5Security/ERP5ExternalOauth2ExtractionPlugin.py b/product/ERP5Security/ERP5ExternalOauth2ExtractionPlugin.py
index 232ffdca71d536aa79a4f53c00420efc71bbce2f..03bdb53c3322515672e9a15dfdcd3d4bce708d40 100644
--- a/product/ERP5Security/ERP5ExternalOauth2ExtractionPlugin.py
+++ b/product/ERP5Security/ERP5ExternalOauth2ExtractionPlugin.py
@@ -197,6 +197,11 @@ class ERP5FacebookExtractionPlugin(ERP5ExternalOauth2ExtractionPlugin, BasePlugi
   header_string = 'facebook'
 
   def getUserEntry(self, token):
+    if facebook is None:
+      LOG('ERP5FacebookExtractionPlugin', INFO,
+          'No facebook module, install facebook-sdk package. '
+            'Authentication disabled.')
+      return None
     timeout = socket.getdefaulttimeout()
     try:
       # require really fast interaction