How to reproduce it :

• connect to cms/_admin
• select a site and click on the button of the ribbon to open le CMS
• A first screen say that we do not have the rights to acceded to this page.
• Click on the button to logout
• the following message appears : Line: 1
  Erreur : L’objet ne gère pas la propriété ou la méthode « remove »

The same appears with the login button that appears on the next screen.