Public bug reported: I have a KVM guest system which was running for some time now (142 days uptime).
Today, I logged in for the first time since months, and got an error message in syslog (and console): kernel: BTRFS error (device vda2): could not find root 8 The error happened together with my login (in respect to the date of the log entry). The system was running with kernel 4.4.0-31-generic when the problem occured. When googling around, I found some similar results, but nowhere is mentioned that this got fixed somehow. So far, I could not find anything harmful (I did not reboot yet, however). I updated the kernel now, eventually that helps. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: linux-image-4.4.0-31-generic 4.4.0-31.50 ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13 Uname: Linux 4.4.0-31-generic x86_64 AlsaDevices: total 0 crw-rw----+ 1 root audio 116, 1 Dec 20 13:00 seq crw-rw----+ 1 root audio 116, 33 Dec 20 13:00 timer AplayDevices: Error: [Errno 2] No such file or directory: 'aplay' ApportVersion: 2.20.1-0ubuntu2.4 Architecture: amd64 ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord' AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: Date: Tue Dec 20 13:40:44 2016 HibernationDevice: RESUME=UUID=419693f3-cd92-4870-a16a-7bede16d9b8a InstallationDate: Installed on 2016-06-20 (182 days ago) InstallationMedia: Ubuntu-Server 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.3) IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig' Lsusb: Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub MachineType: QEMU Standard PC (i440FX + PIIX, 1996) PciMultimedia: ProcEnviron: TERM=linux PATH=(custom, no user) LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 cirrusdrmfb ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-4.4.0-31-generic root=UUID=ebfbbec2-f4df-4e40-92a5-3db6b57eb8f5 ro rootflags=subvol=@ RelatedPackageVersions: linux-restricted-modules-4.4.0-31-generic N/A linux-backports-modules-4.4.0-31-generic N/A linux-firmware 1.157.6 RfKill: Error: [Errno 2] No such file or directory: 'rfkill' SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 04/01/2014 dmi.bios.vendor: SeaBIOS dmi.bios.version: 1.7.5-20140531_083030-gandalf dmi.chassis.type: 1 dmi.chassis.vendor: QEMU dmi.chassis.version: pc-i440fx-2.1 dmi.modalias: dmi:bvnSeaBIOS:bvr1.7.5-20140531_083030-gandalf:bd04/01/2014:svnQEMU:pnStandardPC(i440FX+PIIX,1996):pvrpc-i440fx-2.1:cvnQEMU:ct1:cvrpc-i440fx-2.1: dmi.product.name: Standard PC (i440FX + PIIX, 1996) dmi.product.version: pc-i440fx-2.1 dmi.sys.vendor: QEMU ** Affects: linux (Ubuntu) Importance: Undecided Status: Confirmed ** Tags: amd64 apport-bug xenial -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1651435 Title: BTRFS error: could not find root 8 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1651435/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs