diff --git a/wcs/qommon/sessions.py b/wcs/qommon/sessions.py
index c5744669d..a1e11b9da 100644
--- a/wcs/qommon/sessions.py
+++ b/wcs/qommon/sessions.py
@@ -164,6 +164,8 @@ class Session(QommonSession, CaptchaSession, StorableObject):
     def set_user(self, user_id):  # noqa pylint: disable=arguments-renamed
         self.id = None  # force a new session id to be assigned
         self.extra_user_variables = None
+        self.has_uploads = False
+        self.jsonp_display_values = None
         QuixoteSession.set_user(self, user_id)
         if user_id is None:
             return
diff --git a/wcs/sessions.py b/wcs/sessions.py
index b105bf3f2..37ec7d8b0 100644
--- a/wcs/sessions.py
+++ b/wcs/sessions.py
@@ -115,6 +115,12 @@ class BasicSession(Session):
                 del session.visiting_objects[object_key]
                 session.store()
 
+    def set_user(self, user_id):
+        super().set_user(user_id)
+        if self.user:
+            self.anonymous_formdata_keys = None
+            self.magictokens = None
+
 
 sessions.BasicSession = BasicSession
 StorageSessionManager = sessions.StorageSessionManager