Using Magento CE 2.2.0 with sample data. this error happen when i change time zone in 'bootstrap.php', i try to change it back in it still error.
It's occurred due to MySql TIMESTAMP and MySql version issue.
Here is the solution which helps you to overcome the admin login issue of the session.
Go to :
admin_user_session table in MySql Set
created_at column to '0' and
updated_at column to '
CURRENT_TIMESTAMP' as it is.
Refresh admin page and try to log in again, it will work.