Due to a programming error, users who logged in to a Wikimedia project wiki between 2016-06-07 and 2016-06-14 may have had the "Keep me logged in (for up to 30 days)” setting inadvertently selected, despite the checkbox not having been checked. In order to prevent unauthorized access to user accounts in instances of shared computer use, the Foundation is resetting user sessions for all users who logged in within the aforementioned timeframe. Users who have their session reset will need to log in again.
We apologize for the inconvenience this causes, but we want to reduce the possibility of unintended access to user accounts by unauthorized parties.
Additional information may be found at https://meta.wikimedia.org/wiki/User_session_reset.