I happen to have come across this. I don't have the knowledge to help, but it does sound like this is a kernel issue rather than a problem with the intel-microcode package, so let's reassign it. Otherwise it won't get attention from anyone who might know.
"Critical" importance is probably not correct, but I'll let the kernel team triagers decide that. ** Package changed: intel-microcode (Ubuntu) => linux (Ubuntu) ** Changed in: linux (Ubuntu) Status: Confirmed => New -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1557989 Title: having btrfs installed as the fs is causing a crash when trying to install the intel-microcode package Status in linux package in Ubuntu: New Bug description: I am able to reproduce a bug which causes a kernel panic when the following conditions are met: 1. Xubuntu 16.04 beta 1 is installed 2. btrfs is used as the filesystem 3. The intel-microcode package is installed after the initial system setup is complete I have got an actual photo of the screen when the crash happens as I was unable to locate the correct log file where this would have shown up. I can provide any logs that may be useful ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: ubuntu-release-upgrader-core 1:16.04.7 ProcVersionSignature: Ubuntu 4.4.0-7.22-generic 4.4.2 Uname: Linux 4.4.0-7-generic x86_64 NonfreeKernelModules: nvidia_uvm nvidia ApportVersion: 2.20-0ubuntu3 Architecture: amd64 CrashDB: ubuntu CurrentDesktop: XFCE Date: Wed Mar 16 10:00:14 2016 EcryptfsInUse: Yes InstallationDate: Installed on 2016-03-15 (0 days ago) InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Alpha amd64 (20160224) PackageArchitecture: all SourcePackage: ubuntu-release-upgrader Symptom: release-upgrade UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1557989/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp