VM fails to start: Launch helper exited with unknown return code 1

[Gannet]

Today I found my VM fails to start with the following error:

Помилка під час запуску домену: Launch helper exited with unknown return code 1

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 89, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 125, in tmpcb
    callback(*args, **kwargs)
  File "/usr/share/virt-manager/virtManager/domain.py", line 1360, in startup
    self._backend.create()
  File "/usr/lib/python2.7/dist-packages/libvirt.py", line 1007, in create
    if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
libvirtError: Launch helper exited with unknown return code 1

Linux 3.19RC7 (from here: http://kernel.ubuntu.com/~kernel-ppa/mainline)
Kubuntu 14.10 x86_64
Libvirt-bin: 1.2.12-0~14.10~ppa0
Virt-manager: 1:1.1.0-1~getdeb2
---
ApportVersion: 2.14.7-0ubuntu8.1
Architecture: amd64
CurrentDesktop: KDE
DistroRelease: Ubuntu 14.10
InstallationDate: Installed on 2014-06-08 (245 days ago)
InstallationMedia: Kubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140416.1)
Package: libvirt (not installed)
ProcCmdline: BOOT_IMAGE=/@/boot/vmlinuz-3.19.0-031900rc7-generic root=UUID=b76fc0ae-d31c-4b13-8f4e-424542d850c9 ro rootflags=subvol=@ quiet splash radeon.dpm=1 vt.handoff=7
ProcVersionSignature: Error: [Errno 2] Немає такого файла або каталогу: '/proc/version_signature'
Tags: utopic
Uname: Linux 3.19.0-031900rc7-generic x86_64
UpgradeStatus: Upgraded to utopic on 2014-10-24 (107 days ago)
UserGroups: adm cdrom dip libvirtd lpadmin plugdev sambashare sudo
_MarkForUpload: True
modified.conffile..etc.libvirt.qemu.conf: [inaccessible: [Errno 13] Відмовлено у доступі: u'/etc/libvirt/qemu.conf']
modified.conffile..etc.libvirt.qemu.networks.default.xml: [inaccessible: [Errno 13] Відмовлено у доступі: u'/etc/libvirt/qemu/networks/default.xml']

[Gannet (ken20001)]

apport information

[Gannet (ken20001)]

apport information

[Gannet (ken20001)]

apport information

[Gannet (ken20001)]

libvirtd.log

[Gannet (ken20001)]

It seems it happened after libvirt upgraded from 1.2.11 to 1.2.12.

[Serge Hallyn (serge-hallyn)]

Thanks for reporting this bug.

Apport was unable to upload your /etc/libvirt/qemu.conf file. Please attach it to this bug. If you have a vnc password in your configuration files, please replace it with XXX before uploading.

Did this occur when starting a vm? If so, please provide the /var/log/libvirt/qemu/${VM}.log and the VM configuration xml (virsh dumpxml ${VM}).

[Gannet (ken20001)]

qemu.conf

[Gannet (ken20001)]

Kubuntu-14.04.x-x86-64-15GiB.log

[Gannet (ken20001)]

>If you have a vnc password in your configuration files
No, I don't have one

>Did this occur when starting a vm?
Exactly.

[Gannet (ken20001)]

VM dump XML file

[Gannet (ken20001)]

BTW, I have 6 VMs (4 - linux VMs, 1 - Windows VM and 1 - Android VM) and the result is the same for all of them at start.

[Serge Hallyn (serge-hallyn)]

Thanks. I don't see anything odd in those.

You say you updated from 1.2.11 (from a ppa version) - could you tell us which ppa that came from?

The libvirtd.log shows

2015-02-08 23:54:01.656+0000: 12729: warning : qemuOpenVhostNet:495 : Unable to open vhost-net. Opened so far 0, requested 1

Does /dev/vhost-net exist? If not, does 'modprobe vhost_net' solve this problem?

[Gannet (ken20001)]

>You say you updated from 1.2.11 (from a ppa version) - could you tell us which ppa that came from?
This PPA: ppa:jacob/virtualisation

>Does /dev/vhost-net exist? If not, does 'modprobe vhost_net' solve this problem?
No, it doesn't exist. Yes, 'modprobe vhost_net' solve this. But VM still fails to start with the same message.

[Serge Hallyn (serge-hallyn)]

Quoting Gannet (<email address hidden>):
> >You say you updated from 1.2.11 (from a ppa version) - could you tell us which ppa that came from?
> This PPA: ppa:jacob/virtualisation
>
> >Does /dev/vhost-net exist? If not, does 'modprobe vhost_net' solve this problem?
> No, it doesn't exist. Yes, 'modprobe vhost_net' solve this. But VM still fails to start with the same message.

Yeah sorry by 'solve this problem' I meant the whole problem.

Could you upload your current /var/log/libvirt/libvirtd.log (or just the messages
since Feb 8)?

I looked through the source from the ppa you're using, it doesn't appear to
have any new patches or features enabled, so I don't think that is the cause
of this bug... Were you using that ppa to get newer libvirt versions?

[Gannet (ken20001)]

> Were you using that ppa to get newer libvirt versions?
Not really understood what you mean. I'm using this ppa for several months already.

[Serge Hallyn (serge-hallyn)]

My question was, why did you use the PPA? Was it only to get a newer
version than the 1.2.8 available in vivid at the time, or was there a
feature which it enabled which is not enabled in the archive?

[Serge Hallyn (serge-hallyn)]

Please contact the owner of the PPA. It could also be helpful to test libvirt from the archive (1.2.12-0ubuntu2) and see if that also reproduces the startup error. If it does, then please reply here. (marking invalid as this bug is in a ppa version of the package)

[Gannet (ken20001)]

>My question was, why did you use the PPA?
A-ha. The answer is that i'm using it because first my host-system was Trusty and it had very old versions of VM-components. Then I upgraded to Utopic and I just kept using that PPA to have most fresh versions.

>Please contact the owner of the PPA.
What to ask him?

> It could also be helpful to test libvirt from the archive (1.2.12-0ubuntu2) and see if that also reproduces the startup error.
Just a minute...

[Gannet (ken20001)]

I'm sorry but I can't try 1.2.12 from Vivid because of too much broken dependencies.

[Gannet (ken20001)]

Just a minute ago some updates installed after which my VMs now starting well O_O The following packages was updated:

libkrb5support0:i386 (1.12.1+dfsg-10ubuntu0.1)
libkrb5support0:amd64 (1.12.1+dfsg-10ubuntu0.1)
libk5crypto3:i386 (1.12.1+dfsg-10ubuntu0.1)
libk5crypto3:amd64 (1.12.1+dfsg-10ubuntu0.1)
libkrb5-3:i386 (1.12.1+dfsg-10ubuntu0.1)
libkrb5-3:amd64 (1.12.1+dfsg-10ubuntu0.1)
libgssapi-krb5-2:i386 (1.12.1+dfsg-10ubuntu0.1)
libgssapi-krb5-2:amd64 (1.12.1+dfsg-10ubuntu0.1)
krb5-locales (1.12.1+dfsg-10ubuntu0.1)

I don't know which of them solves the issue.

[Gannet (ken20001)]

OMG, today it fails again... о_О There is something strange happening...