Migration V11 (staging) : error 500

Traceback (most recent call last):
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/app.py", line 58, in application
    init_request(request)
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/app.py", line 120, in init_request
    frappe.local.http_request = frappe.auth.HTTPRequest()
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/auth.py", line 51, in __init__
    frappe.local.login_manager = LoginManager()
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/auth.py", line 113, in __init__
    self.make_session(resume=True)
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/auth.py", line 182, in make_session
    full_name=self.full_name, user_type=self.user_type)
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/sessions.py", line 194, in __init__
    self.resume()
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/sessions.py", line 249, in resume
    data = self.get_session_record()
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/sessions.py", line 266, in get_session_record
    r = self.get_session_data()
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/sessions.py", line 282, in get_session_data
    data = self.get_session_data_from_db()
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/sessions.py", line 309, in get_session_data_from_db
    get_expiry_period(self.device)))
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/sessions.py", line 379, in get_expiry_period
    exp_sec = frappe.defaults.get_global_default(key) or default
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/defaults.py", line 99, in get_global_default
    if not_in_user_permission(key, value):
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/defaults.py", line 61, in not_in_user_permission
    user_permission = get_user_permissions(user).get(frappe.unscrub(key))
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/defaults.py", line 68, in get_user_permissions
    return _get_user_permissions(user)
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/core/doctype/user_permission/user_permission.py", line 59, in get_user_permissions
    out[perm.allow]["docs"].extend(frappe.db.get_descendants(perm.allow, perm.for_value))
  File "/home/frappe/auroraone-v11/apps/frappe/frappe/database.py", line 970, in get_descendants
    lft, rgt = self.get_value(doctype, name, ('lft', 'rgt'))
TypeError: 'NoneType' object is not iterable

Strange, which migration script is missing ?