WordPress 4.0 was released on 4th September 2014.

Update to WordPress 4.0 using the same process as shown for WordPress 3.6

Remember

Before applying any update remember to take a backup and confirm that the backup file will unpack.

See also

• WordPress 4.0 "Benny"
• Perform backups
• You should also update the oik base plugin to version 2.2 or higher.
• While you’re at it update other oik plugins from WordPress.org