Google Play Store not working after upgrade to Android 6.0.1

[AC Question]

Hello all, following the upgrade of my OS to Android 6.0.1, I receive an error message related to Google Play Store. I cannot use the app any more. I have One X Plus and an Italian carrier (Tim). Could you suggest me a solution or workaround? I have tried to close the app but all options in the Manage app menu are greyed out.
thanks