I'm not sure if this is the cause or a red herring, but I found this on one of the machines which got stuck on boot. Other instances usually don't print anything.
** Attachment added: "Untitled2.png" https://bugs.launchpad.net/ubuntu/+source/linux-meta-lts-xenial/+bug/1751294/+attachment/5082309/+files/Untitled2.png -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1751294 Title: Kernel linux-image-4.4.0-112-generic prevent the boot on Microsoft Hyper-v 2016 Gen2 VM To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-meta-lts-xenial/+bug/1751294/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
