With latest 4.4.0-109-generic version of the Linux kernel, users can download it from a mirror or temporarily switch to “Main server” (http://archive.ubuntu.com/ubuntu) and get it from here. For those who affected: Remove 108 kernel with purge linux-headers-4.4.0-108-generic linux-image-extra and get the latest version. Wait for 109 kernel to appear on your mirror or switch to Main server.”]
Source: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1741934/comments/46