diff --git a/README.md b/README.md
index ea0de2a..defd426 100644
--- a/README.md
+++ b/README.md
@@ -46,6 +46,10 @@ provided in input JSON file to a map of fetched data by this module.
 Each module map has a `cookies` entry containing the cookies used to fetch the
 data, so that any program running afterwards can download documents.
 
+**Important** note: Most of such websites have very short lived sessions,
+meaning in most cases these `cookies` will be useless for extra download as
+the session will most likely be destroyed on the server side.
+
 The other entries in these maps depend on the module capabilities as defined
 by Weboob. Detailed informations about these other entires can be found in the
 `doc/capabilities` folder.
diff --git a/tools/progress.py b/tools/progress.py
index 97b232e..82a2afc 100644
--- a/tools/progress.py
+++ b/tools/progress.py
@@ -12,3 +12,12 @@ class DummyProgress:
         Progress function. Do nothing.
         """
         pass
+
+    def error(self, message):
+        """
+        Error function. Do nothing.
+        """
+        pass
+
+    def prompt(self, message):
+        raise NotImplementedError()