--- a/cubicweb/server/hook.py	Sat Feb 01 22:01:00 2020 +0100
+++ b/cubicweb/server/hook.py	Tue Feb 11 10:20:18 2020 +0100
@@ -522,8 +522,8 @@
     """
     __select__ = enabled_category()
     # set this in derivated classes
+    category = None
     events: Union[None, Tuple[str], Tuple[str, str]] = None
-    category: Union[None, str] = None
     order = 0
     # stop pylint from complaining about missing attributes in Hooks classes
     eidfrom = eidto = entity = rtype = repo = None

--- a/cubicweb/web/action.py	Sat Feb 01 22:01:00 2020 +0100
+++ b/cubicweb/web/action.py	Tue Feb 11 10:20:18 2020 +0100
@@ -32,7 +32,6 @@
 Many examples are available in :mod:`cubicweb.web.views.actions`.
 """
 
-from typing import Optional
 
 from cubicweb import _
 
@@ -49,7 +48,7 @@
     __registry__ = 'actions'
     __select__ = match_search_state('normal')
     order = 99
-    category: Optional[str] = 'moreactions'
+    category = 'moreactions'
     # actions in category 'moreactions' can specify a sub-menu in which they should be filed
     submenu = None