16.0a2: about:preferences#privacy is empty

log:

Uncaught (in promise) TypeError: can't access property "removeAttribute", notificationsDoNotDisturbBox is null
    init chrome://browser/content/preferences/privacy.js:3606
    init chrome://browser/content/preferences/preferences.js:324
    gotoPref chrome://browser/content/preferences/preferences.js:540
    init_all chrome://browser/content/preferences/preferences.js:415
privacy.js:3606:7