Hello, I opened a bug (http://bugzilla.redhat.com/show_bug.cgi?id=757138) about this issue, but I was told to mention it to this list too. Here is my problem : when I try to start a virtualbox domain with virsh, an error occurs. (But when the domain is started using Virtualbox GUI it works, and I have no problem to stop it with virsh...) Example : virsh # start freenas1 error: Failed to start domain freenas1 error: An error occurred, but the cause is unknown I use libvirt 0.9.2-7 and virtualbox 4.0.10 on a Debian with 2.6.32-5-amd64 kernel. The XML config file of the domain : <domain type='vbox' id='1'>   <name>freenas1</name>   <uuid>07aadf11-2090-4690-9518-52766722c544</uuid>   <memory>524288</memory>   <currentMemory>524288</currentMemory>   <vcpu>1</vcpu>   <os>     <type arch='x86_64'>hvm</type>     <boot dev='hd'/>   </os>   <features>     <acpi/>     <apic/>   </features>   <clock offset='localtime'/>   <on_poweroff>destroy</on_poweroff>   <on_reboot>destroy</on_reboot>   <on_crash>destroy</on_crash>   <devices>     <disk type='file' device='disk'>       <source file='/data/Freenas1Disk1.vdi'/>       <target dev='hda' bus='ide'/>     </disk>     <input type='mouse' bus='ps2'/>     <graphics type='desktop' display='localhost:10.0'/>     <video>       <model type='vbox' vram='8192' heads='1'>         <acceleration accel3d='no' accel2d='no'/>       </model>     </video>   </devices> </domain> virsh debug output : virsh # start freenas1 15:51:31.043: 5796: debug : virConnectOpenAuth:1328 : name=(null), auth=0x7f19ee32d320, flags=0 15:51:31.043: 5796: debug : do_open:1065 : no name, allowing driver auto-select 15:51:31.043: 5796: debug : do_open:1102 : trying driver 0 (Test) ... 15:51:31.043: 5796: debug : do_open:1108 : driver 0 Test returned DECLINED 15:51:31.043: 5796: debug : do_open:1102 : trying driver 1 (Xen) ... 15:51:31.043: 5796: debug : do_open:1108 : driver 1 Xen returned DECLINED 15:51:31.043: 5796: debug : do_open:1102 : trying driver 2 (OPENVZ) ... 15:51:31.043: 5796: debug : do_open:1108 : driver 2 OPENVZ returned DECLINED 15:51:31.043: 5796: debug : do_open:1102 : trying driver 3 (VMWARE) ... 15:51:31.043: 5796: debug : do_open:1108 : driver 3 VMWARE returned DECLINED 15:51:31.043: 5796: debug : do_open:1102 : trying driver 4 (VBOX) ... 15:51:31.050: 5796: debug : vboxOpen:1035 : in vboxOpen 15:51:31.050: 5796: debug : do_open:1108 : driver 4 VBOX returned SUCCESS 15:51:31.050: 5796: debug : do_open:1130 : network driver 0 Test returned DECLINED 15:51:31.050: 5796: debug : vboxNetworkOpen:6953 : network initialized 15:51:31.050: 5796: debug : do_open:1130 : network driver 1 VBOX returned SUCCESS 15:51:31.050: 5796: debug : do_open:1145 : interface driver 0 Test returned DECLINED 15:51:31.051: 5796: debug : doRemoteOpen:596 : proceeding with name = vbox:///system 15:51:31.051: 5796: debug : remoteIO:5824 : Do proc=66 serial=0 length=28 wait=(nil) 15:51:31.051: 5796: debug : remoteIO:5896 : We have the buck 66 0x7f19e6c37010 0x7f19e6c37010 15:51:31.051: 5796: debug : remoteIODecodeMessageLength:5214 : Got length, now need 64 total (60 more) 15:51:31.051: 5796: debug : remoteIOEventLoop:5750 : Giving up the buck 66 0x7f19e6c37010 (nil) 15:51:31.051: 5796: debug : remoteIO:5924 : All done with our call 66 (nil) 0x7f19e6c37010 15:51:31.051: 5796: debug : remoteIO:5824 : Do proc=1 serial=1 length=56 wait=(nil) 15:51:31.051: 5796: debug : remoteIO:5896 : We have the buck 1 0x7f19e003fec0 0x7f19e003fec0 15:51:31.052: 5796: debug : remoteIODecodeMessageLength:5214 : Got length, now need 176 total (172 more) 15:51:31.052: 5796: debug : remoteIOEventLoop:5750 : Giving up the buck 1 0x7f19e003fec0 (nil) 15:51:31.052: 5796: debug : remoteIO:5924 : All done with our call 1 (nil) 0x7f19e003fec0 15:51:31.052: 5796: debug : do_open:1145 : interface driver 1 remote returned ERROR 15:51:31.052: 5796: debug : do_open:1161 : storage driver 0 Test returned DECLINED 15:51:31.052: 5796: debug : vboxStorageOpen:7764 : vbox storage initialized 15:51:31.052: 5796: debug : do_open:1161 : storage driver 1 VBOX returned SUCCESS 15:51:31.052: 5796: debug : do_open:1177 : node driver 0 Test returned DECLINED 15:51:31.053: 5796: debug : doRemoteOpen:596 : proceeding with name = vbox:///system 15:51:31.053: 5796: debug : remoteIO:5824 : Do proc=66 serial=0 length=28 wait=(nil) 15:51:31.053: 5796: debug : remoteIO:5896 : We have the buck 66 0x7f19e0081f90 0x7f19e0081f90 15:51:31.054: 5796: debug : remoteIODecodeMessageLength:5214 : Got length, now need 64 total (60 more) 15:51:31.054: 5796: debug : remoteIOEventLoop:5750 : Giving up the buck 66 0x7f19e0081f90 (nil) 15:51:31.054: 5796: debug : remoteIO:5924 : All done with our call 66 (nil) 0x7f19e0081f90 15:51:31.054: 5796: debug : remoteIO:5824 : Do proc=1 serial=1 length=56 wait=(nil) 15:51:31.054: 5796: debug : remoteIO:5896 : We have the buck 1 0x7f19e0081f90 0x7f19e0081f90 15:51:31.055: 5796: debug : remoteIODecodeMessageLength:5214 : Got length, now need 176 total (172 more) 15:51:31.055: 5796: debug : remoteIOEventLoop:5750 : Giving up the buck 1 0x7f19e0081f90 (nil) 15:51:31.055: 5796: debug : remoteIO:5924 : All done with our call 1 (nil) 0x7f19e0081f90 15:51:31.055: 5796: debug : do_open:1177 : node driver 1 remote returned ERROR 15:51:31.055: 5796: debug : do_open:1193 : secret driver 0 Test returned DECLINED 15:51:31.055: 5796: debug : doRemoteOpen:596 : proceeding with name = vbox:///system 15:51:31.055: 5796: debug : remoteIO:5824 : Do proc=66 serial=0 length=28 wait=(nil) 15:51:31.055: 5796: debug : remoteIO:5896 : We have the buck 66 0x7f19e0081f90 0x7f19e0081f90 15:51:31.056: 5796: debug : remoteIODecodeMessageLength:5214 : Got length, now need 64 total (60 more) 15:51:31.056: 5796: debug : remoteIOEventLoop:5750 : Giving up the buck 66 0x7f19e0081f90 (nil) 15:51:31.056: 5796: debug : remoteIO:5924 : All done with our call 66 (nil) 0x7f19e0081f90 15:51:31.056: 5796: debug : remoteIO:5824 : Do proc=1 serial=1 length=56 wait=(nil) 15:51:31.056: 5796: debug : remoteIO:5896 : We have the buck 1 0x7f19e0081f90 0x7f19e0081f90 15:51:31.057: 5796: debug : remoteIODecodeMessageLength:5214 : Got length, now need 176 total (172 more) 15:51:31.057: 5796: debug : remoteIOEventLoop:5750 : Giving up the buck 1 0x7f19e0081f90 (nil) 15:51:31.057: 5796: debug : remoteIO:5924 : All done with our call 1 (nil) 0x7f19e0081f90 15:51:31.057: 5796: debug : do_open:1193 : secret driver 1 remote returned ERROR 15:51:31.057: 5796: debug : do_open:1209 : nwfilter driver 0 Test returned DECLINED 15:51:31.057: 5796: debug : doRemoteOpen:596 : proceeding with name = vbox:///system 15:51:31.057: 5796: debug : remoteIO:5824 : Do proc=66 serial=0 length=28 wait=(nil) 15:51:31.057: 5796: debug : remoteIO:5896 : We have the buck 66 0x7f19e0081f90 0x7f19e0081f90 15:51:31.058: 5796: debug : remoteIODecodeMessageLength:5214 : Got length, now need 64 total (60 more) 15:51:31.058: 5796: debug : remoteIOEventLoop:5750 : Giving up the buck 66 0x7f19e0081f90 (nil) 15:51:31.058: 5796: debug : remoteIO:5924 : All done with our call 66 (nil) 0x7f19e0081f90 15:51:31.058: 5796: debug : remoteIO:5824 : Do proc=1 serial=1 length=56 wait=(nil) 15:51:31.058: 5796: debug : remoteIO:5896 : We have the buck 1 0x7f19e0081f90 0x7f19e0081f90 15:51:31.059: 5796: debug : remoteIODecodeMessageLength:5214 : Got length, now need 176 total (172 more) 15:51:31.059: 5796: debug : remoteIOEventLoop:5750 : Giving up the buck 1 0x7f19e0081f90 (nil) 15:51:31.059: 5796: debug : remoteIO:5924 : All done with our call 1 (nil) 0x7f19e0081f90 15:51:31.059: 5796: debug : do_open:1209 : nwfilter driver 1 remote returned ERROR 15:51:31.060: 5796: debug : virDomainLookupByName:2030 : conn=0x6f6350, name=freenas1 15:51:31.061: 5796: debug : virDomainGetID:2718 : dom=0x7f19e002db00, (VM: name=freenas1, uuid=07aadf11-2090-4690-9518-52766722c544), 15:51:31.061: 5796: debug : virDomainCreate:6300 : dom=0x7f19e002db00, (VM: name=freenas1, uuid=07aadf11-2090-4690-9518-52766722c544), 15:51:31.566: 5796: debug : virDomainGetName:2623 : domain=0x7f19e002db00 error: Failed to start domain freenas1 15:51:31.566: 5796: debug : virDomainFree:2118 : dom=0x7f19e002db00, (VM: name=freenas1, uuid=07aadf11-2090-4690-9518-52766722c544), 15:51:31.566: 5796: debug : virUnrefDomain:276 : unref domain 0x7f19e002db00 freenas1 1 15:51:31.566: 5796: debug : virReleaseDomain:238 : release domain 0x7f19e002db00 freenas1 07aadf11-2090-4690-9518-52766722c544 15:51:31.566: 5796: debug : virReleaseDomain:246 : unref connection 0x6f6350 2 error: An error occurred, but the cause is unknown ##### I f you have an idea of what the problem is... Thank you, jC