Since recently, the plugin failed to start any of my VBox machines.

I'm not sure if this is a bug in the vboxwebsrv application or if the virtualbox plugin is sending the wrong commands, but this is the output on Jenkins slave log:

[VirtualBox] Launching node server-1210-amd64
[VirtualBox] Powering up VirtualBoxMachine{host=VirtualBoxHost

{url='http://vader:18083', username='virtual'}

,name='server-1210-amd64'}...
[VirtualBox] Lost connection to http://vader:18083, reconnecting
[VirtualBox] Trying to connect to http://vader:18083, user virtual
[VirtualBox] Creating connection to VirtualBox version 4.2.6
[VirtualBox] Connected to VirtualBox version 4.2.6 on host http://vader:18083
[VirtualBox] starting node server-1210-amd64 from state Saved
FATAL: [VirtualBox] node server-1210-amd64 error: The virtual machine 'server-1210-amd64' has terminated unexpectedly during startup with exit code 0

FATAL: Unable to launch

And this is what we see on vboxwebsrv -v :

Oracle VM VirtualBox web service Version 4.2.6
(C) 2007-2012 Oracle Corporation
All rights reserved.
VirtualBox web service 4.2.6 r82870 linux.amd64 (Dec 19 2012 15:09:30) release log
00:00:00.015733 main Log opened 2013-01-18T09:09:31.200070000Z
00:00:00.015740 main OS Product: Linux
00:00:00.015742 main OS Release: 3.2.0-35-generic
00:00:00.015743 main OS Version: #55-Ubuntu SMP Wed Dec 5 17:42:16 UTC 2012
00:00:00.015775 main DMI Product Name: System Product Name
00:00:00.015785 main DMI Product Version: System Version
00:00:00.015795 main Host RAM: 24104MB total, 2972MB available
00:00:00.015799 main Executable: /usr/lib/virtualbox/vboxwebsrv
00:00:00.015800 main Process ID: 560
00:00:00.015801 main Package type: LINUX_64BITS_UBUNTU_12_04
00:00:00.022241 main Pumping COM event queue
00:00:00.022271 main Pumping COM event queue
00:00:00.022356 Watchdog Watchdog thread started
00:00:00.022383 Watchdog Watchdog: sleeping 5 seconds
00:00:00.025370 SQPmp Socket connection successful: host = default (localhost), port = 18083, master socket = 8
00:00:05.022484 Watchdog Watchdog: checking 0 sessions
00:00:05.022555 Watchdog Watchdog: sleeping 5 seconds
00:00:10.022617 Watchdog Watchdog: checking 0 sessions
00:00:10.022691 Watchdog Watchdog: sleeping 5 seconds
00:00:12.330449 SQPmp Request 1 on socket 10 queued for processing (1 items on Q)
00:00:12.330538 SQW01 New SOAP thread started
00:00:12.330570 SQW01 Processing connection from IP=127.0.0.1 socket=10 (0 out of 1 threads idle)
00:00:12.356091 SQW01 – entering _vbox_IVirtualBox_USCOREgetVersion
00:00:12.356110 SQW01 findRefFromId(): looking up objref 35869155d6a20050-0000000000000004
00:00:12.356121 SQW01 findRefFromId: cannot find session for objref 35869155d6a20050-0000000000000004
00:00:12.356165 SQW01 – leaving _vbox_IVirtualBox_USCOREgetVersion, rc: 0xFFFFEF32 (-4302)
00:00:12.358599 SQPmp Request 2 on socket 11 queued for processing (1 items on Q)
00:00:12.358649 SQW01 Processing connection from IP=127.0.0.1 socket=11 (0 out of 1 threads idle)
00:00:12.359034 SQW01 – entering _vbox_IWebsessionManager_USCORElogon
00:00:12.359638 main Pumping COM event queue
00:00:12.361551 main Pumping COM event queue
00:00:12.361919 main Pumping COM event queue
00:00:12.361992 SQW01 external authentication library is 'null'
00:00:12.362225 SQW01 * ManagedObjectRef: MOR created for ISession*=0x7FD3100216C0 (IUnknown*=0x7FD3100216C0; COM refcount now 3/4), new ID is 1; now 1 objects total
00:00:12.362241 SQW01 * authenticate: created session object with comptr 0x7FD3100216C0, MOR = 0a39b81ff238d417-0000000000000001
00:00:12.362632 main Pumping COM event queue
00:00:12.362651 SQW01 * ManagedObjectRef: MOR created for IVirtualBox*=0x1785190 (IUnknown*=0x7FD3100246A0; COM refcount now 3/4), new ID is 2; now 2 objects total
00:00:12.362664 SQW01 VirtualBox object ref is 0a39b81ff238d417-0000000000000002
00:00:12.362671 SQW01 – leaving _vbox_IWebsessionManager_USCORElogon, rc: 0x0
00:00:12.363642 SQW01 – entering _vbox_IVirtualBox_USCOREgetVersion
00:00:12.363655 SQW01 findRefFromId(): looking up objref 0a39b81ff238d417-0000000000000002
00:00:12.363665 SQW01 findComPtrFromId(): returning original IVirtualBox*=0x1785190 (IUnknown*=0x7FD3100246A0)
00:00:12.363671 SQW01 calling COM method COMGETTER(Version)
00:00:12.364070 main Pumping COM event queue
00:00:12.364085 SQW01 done calling COM method
00:00:12.364101 SQW01 convert COM output "version" back to caller format
00:00:12.364111 SQW01 done converting COM output "version" back to caller format
00:00:12.364121 SQW01 – leaving _vbox_IVirtualBox_USCOREgetVersion, rc: 0x0 (0)
00:00:12.365013 SQW01 – entering _vbox_IWebsessionManager_USCORElogoff
00:00:12.365043 SQW01 * ~ManagedObjectRef: deleting MOR for ID 1 (ISession; COM refcount now 0/1); now 1 objects total
00:00:12.365056 SQW01 * ~ManagedObjectRef: deleting MOR for ID 2 (IVirtualBox; COM refcount now 1/2); now 0 objects total
00:00:12.365063 SQW01 session destroyed, 0 sessions left open
00:00:12.365068 SQW01 – leaving _vbox_IWebsessionManager_USCORElogoff, rc: 0x0
00:00:12.366593 SQW01 – entering _vbox_IWebsessionManager_USCORElogon
00:00:12.367028 main Pumping COM event queue
00:00:12.367048 SQW01 * ManagedObjectRef: MOR created for ISession*=0x7FD31002B350 (IUnknown*=0x7FD31002B350; COM refcount now 3/4), new ID is 3; now 1 objects total
00:00:12.367079 SQW01 * authenticate: created session object with comptr 0x7FD31002B350, MOR = f668692f2fb1c9ba-0000000000000003
00:00:12.367262 SQW01 * ManagedObjectRef: MOR created for IVirtualBox*=0x1785190 (IUnknown*=0x7FD3100246A0; COM refcount now 3/4), new ID is 4; now 2 objects total
00:00:12.367272 SQW01 VirtualBox object ref is f668692f2fb1c9ba-0000000000000004
00:00:12.367278 SQW01 – leaving _vbox_IWebsessionManager_USCORElogon, rc: 0x0
00:00:12.368120 SQW01 – entering _vbox_IVirtualBox_USCOREfindMachine
00:00:12.368135 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000004
00:00:12.368144 SQW01 findComPtrFromId(): returning original IVirtualBox*=0x1785190 (IUnknown*=0x7FD3100246A0)
00:00:12.368157 SQW01 calling COM method FindMachine
00:00:12.368675 SQW01 done calling COM method
00:00:12.368719 main Pumping COM event queue
00:00:12.368785 SQW01 convert COM output "returnval" back to caller format
00:00:12.368982 main Pumping COM event queue
00:00:12.369017 SQW01 * ManagedObjectRef: MOR created for IMachine*=0x7FD31002DAA0 (IUnknown*=0x7FD3100325E0; COM refcount now 3/2), new ID is 5; now 3 objects total
00:00:12.369028 SQW01 done converting COM output "returnval" back to caller format
00:00:12.369035 SQW01 – leaving _vbox_IVirtualBox_USCOREfindMachine, rc: 0x0 (0)
00:00:12.369610 SQW01 – entering _vbox_IMachine_USCOREgetState
00:00:12.369620 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000005
00:00:12.369625 SQW01 findComPtrFromId(): returning original IMachine*=0x7FD31002DAA0 (IUnknown*=0x7FD3100325E0)
00:00:12.369629 SQW01 calling COM method COMGETTER(State)
00:00:12.369870 main Pumping COM event queue
00:00:12.369892 SQW01 done calling COM method
00:00:12.369901 SQW01 convert COM output "state" back to caller format
00:00:12.369911 SQW01 done converting COM output "state" back to caller format
00:00:12.369916 SQW01 – leaving _vbox_IMachine_USCOREgetState, rc: 0x0 (0)
00:00:12.370683 SQW01 – entering _vbox_IWebsessionManager_USCOREgetSessionObject
00:00:12.370699 SQW01 – leaving _vbox_IWebsessionManager_USCOREgetSessionObject, rc: 0x0
00:00:12.371484 SQW01 – entering _vbox_ISession_USCOREgetState
00:00:12.371500 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000003
00:00:12.371510 SQW01 findComPtrFromId(): returning original ISession*=0x7FD31002B350 (IUnknown*=0x7FD31002B350)
00:00:12.371516 SQW01 calling COM method COMGETTER(State)
00:00:12.371527 SQW01 done calling COM method
00:00:12.371531 SQW01 convert COM output "state" back to caller format
00:00:12.371536 SQW01 done converting COM output "state" back to caller format
00:00:12.371541 SQW01 – leaving _vbox_ISession_USCOREgetState, rc: 0x0 (0)
00:00:12.372374 SQW01 – entering _vbox_IMachine_USCORElaunchVMProcess
00:00:12.372388 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000005
00:00:12.372396 SQW01 findComPtrFromId(): returning original IMachine*=0x7FD31002DAA0 (IUnknown*=0x7FD3100325E0)
00:00:12.372402 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000003
00:00:12.372408 SQW01 findComPtrFromId(): returning original ISession*=0x7FD31002B350 (IUnknown*=0x7FD31002B350)
00:00:12.372416 SQW01 calling COM method LaunchVMProcess
00:00:12.372765 main Pumping COM event queue
00:00:12.373019 main Pumping COM event queue
00:00:12.373784 main Pumping COM event queue
00:00:12.374260 main Pumping COM event queue
00:00:12.374279 SQW01 done calling COM method
00:00:12.374289 SQW01 convert COM output "returnval" back to caller format
00:00:12.374338 main Pumping COM event queue
00:00:12.374456 main Pumping COM event queue
00:00:12.374469 SQW01 * ManagedObjectRef: MOR created for IProgress*=0x7FD310005E40 (IUnknown*=0x7FD310005F10; COM refcount now 3/2), new ID is 6; now 4 objects total
00:00:12.374481 SQW01 done converting COM output "returnval" back to caller format
00:00:12.374487 SQW01 – leaving _vbox_IMachine_USCORElaunchVMProcess, rc: 0x0 (0)
00:00:12.374998 SQW01 – entering _vbox_IProgress_USCOREwaitForCompletion
00:00:12.375008 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000006
00:00:12.375012 SQW01 findComPtrFromId(): returning original IProgress*=0x7FD310005E40 (IUnknown*=0x7FD310005F10)
00:00:12.375015 SQW01 calling COM method WaitForCompletion
00:00:12.459963 main Pumping COM event queue
00:00:12.460296 main Pumping COM event queue
00:00:12.460507 main Pumping COM event queue
00:00:12.460534 SQW01 done calling COM method
00:00:12.460558 SQW01 – leaving _vbox_IProgress_USCOREwaitForCompletion, rc: 0x0 (0)
00:00:12.461570 SQW01 – entering _vbox_IProgress_USCOREgetResultCode
00:00:12.461587 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000006
00:00:12.461597 SQW01 findComPtrFromId(): returning original IProgress*=0x7FD310005E40 (IUnknown*=0x7FD310005F10)
00:00:12.461603 SQW01 calling COM method COMGETTER(ResultCode)
00:00:12.462061 main Pumping COM event queue
00:00:12.462080 SQW01 done calling COM method
00:00:12.462099 SQW01 convert COM output "resultCode" back to caller format
00:00:12.462115 SQW01 done converting COM output "resultCode" back to caller format
00:00:12.462126 SQW01 – leaving _vbox_IProgress_USCOREgetResultCode, rc: 0x0 (0)
00:00:12.462971 SQW01 – entering _vbox_IMachine_USCOREgetSessionState
00:00:12.462986 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000005
00:00:12.462995 SQW01 findComPtrFromId(): returning original IMachine*=0x7FD31002DAA0 (IUnknown*=0x7FD3100325E0)
00:00:12.463001 SQW01 calling COM method COMGETTER(SessionState)
00:00:12.463337 SQW01 done calling COM method
00:00:12.463362 main Pumping COM event queue
00:00:12.463393 SQW01 convert COM output "sessionState" back to caller format
00:00:12.463403 SQW01 done converting COM output "sessionState" back to caller format
00:00:12.463410 SQW01 – leaving _vbox_IMachine_USCOREgetSessionState, rc: 0x0 (0)
00:00:12.464341 SQW01 – entering _vbox_ISession_USCOREgetState
00:00:12.464356 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000003
00:00:12.464364 SQW01 findComPtrFromId(): returning original ISession*=0x7FD31002B350 (IUnknown*=0x7FD31002B350)
00:00:12.464370 SQW01 calling COM method COMGETTER(State)
00:00:12.464378 SQW01 done calling COM method
00:00:12.464383 SQW01 convert COM output "state" back to caller format
00:00:12.464387 SQW01 done converting COM output "state" back to caller format
00:00:12.464392 SQW01 – leaving _vbox_ISession_USCOREgetState, rc: 0x0 (0)
00:00:12.465232 SQW01 – entering _vbox_ISession_USCOREunlockMachine
00:00:12.465247 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000003
00:00:12.465255 SQW01 findComPtrFromId(): returning original ISession*=0x7FD31002B350 (IUnknown*=0x7FD31002B350)
00:00:12.465261 SQW01 calling COM method UnlockMachine
00:00:12.465280 SQW01 ERROR [COM]: aRC=NS_ERROR_UNEXPECTED (0x8000ffff) aIID=

{12f4dcdb-12b2-4ec1-b7cd-ddd9f6c5bf4d}

aComponent=

{Session}

aText=

{The session is not locked (session state: Unlocked)}

, preserve=false
00:00:12.465366 SQW01 error, raising SOAP exception
00:00:12.465375 SQW01 API return code: 0x8000FFFF (NS_ERROR_UNEXPECTED)
00:00:12.465380 SQW01 COM error info result code: 0x8000FFFF
00:00:12.465386 SQW01 COM error info text: The session is not locked (session state: Unlocked)
00:00:12.465405 SQW01 – leaving _vbox_ISession_USCOREunlockMachine, rc: 0x8000FFFF (-2147418113)
00:00:12.467237 SQPmp Request 3 on socket 10 queued for processing (1 items on Q)
00:00:12.467277 SQW01 Processing connection from IP=127.0.0.1 socket=10 (0 out of 1 threads idle)
00:00:12.467556 SQW01 – entering _vbox_IMachine_USCOREgetSessionState
00:00:12.467586 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000005
00:00:12.467609 SQW01 findComPtrFromId(): returning original IMachine*=0x7FD31002DAA0 (IUnknown*=0x7FD3100325E0)
00:00:12.467632 SQW01 calling COM method COMGETTER(SessionState)
00:00:12.467901 main Pumping COM event queue
00:00:12.467929 SQW01 done calling COM method
00:00:12.467963 SQW01 convert COM output "sessionState" back to caller format
00:00:12.467988 SQW01 done converting COM output "sessionState" back to caller format
00:00:12.468010 SQW01 – leaving _vbox_IMachine_USCOREgetSessionState, rc: 0x0 (0)
00:00:12.468800 SQW01 – entering _vbox_ISession_USCOREgetState
00:00:12.468828 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000003
00:00:12.468852 SQW01 findComPtrFromId(): returning original ISession*=0x7FD31002B350 (IUnknown*=0x7FD31002B350)
00:00:12.468874 SQW01 calling COM method COMGETTER(State)
00:00:12.468897 SQW01 done calling COM method
00:00:12.468917 SQW01 convert COM output "state" back to caller format
00:00:12.468937 SQW01 done converting COM output "state" back to caller format
00:00:12.468959 SQW01 – leaving _vbox_ISession_USCOREgetState, rc: 0x0 (0)
00:00:12.469728 SQW01 – entering _vbox_IProgress_USCOREgetResultCode
00:00:12.469758 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000006
00:00:12.469780 SQW01 findComPtrFromId(): returning original IProgress*=0x7FD310005E40 (IUnknown*=0x7FD310005F10)
00:00:12.469803 SQW01 calling COM method COMGETTER(ResultCode)
00:00:12.470201 main Pumping COM event queue
00:00:12.470256 SQW01 done calling COM method
00:00:12.470325 SQW01 convert COM output "resultCode" back to caller format
00:00:12.470364 SQW01 done converting COM output "resultCode" back to caller format
00:00:12.470387 SQW01 – leaving _vbox_IProgress_USCOREgetResultCode, rc: 0x0 (0)
00:00:12.471225 SQW01 – entering _vbox_IProgress_USCOREgetErrorInfo
00:00:12.471253 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000006
00:00:12.471276 SQW01 findComPtrFromId(): returning original IProgress*=0x7FD310005E40 (IUnknown*=0x7FD310005F10)
00:00:12.471299 SQW01 calling COM method COMGETTER(ErrorInfo)
00:00:12.471572 SQW01 done calling COM method
00:00:12.471592 main Pumping COM event queue
00:00:12.471637 SQW01 convert COM output "errorInfo" back to caller format
00:00:12.471846 main Pumping COM event queue
00:00:12.471882 SQW01 * ManagedObjectRef: MOR created for IVirtualBoxErrorInfo*=0x7FD310006A00 (IUnknown*=0x7FD310006AA0; COM refcount now 3/2), new ID is 7; now 5 objects total
00:00:12.471902 SQW01 done converting COM output "errorInfo" back to caller format
00:00:12.471912 SQW01 – leaving _vbox_IProgress_USCOREgetErrorInfo, rc: 0x0 (0)
00:00:12.472674 SQW01 – entering _vbox_IVirtualBoxErrorInfo_USCOREgetText
00:00:12.472718 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000007
00:00:12.472745 SQW01 findComPtrFromId(): returning original IVirtualBoxErrorInfo*=0x7FD310006A00 (IUnknown*=0x7FD310006AA0)
00:00:12.472767 SQW01 calling COM method COMGETTER(Text)
00:00:12.473008 main Pumping COM event queue
00:00:12.473079 SQW01 done calling COM method
00:00:12.473104 SQW01 convert COM output "text" back to caller format
00:00:12.473127 SQW01 done converting COM output "text" back to caller format
00:00:12.473150 SQW01 – leaving _vbox_IVirtualBoxErrorInfo_USCOREgetText, rc: 0x0 (0)
00:00:12.474023 SQW01 – entering _vbox_IVirtualBoxErrorInfo_USCOREgetNext
00:00:12.474038 SQW01 findRefFromId(): looking up objref f668692f2fb1c9ba-0000000000000007
00:00:12.474046 SQW01 findComPtrFromId(): returning original IVirtualBoxErrorInfo*=0x7FD310006A00 (IUnknown*=0x7FD310006AA0)
00:00:12.474056 SQW01 calling COM method COMGETTER(Next)
00:00:12.474283 main Pumping COM event queue
00:00:12.474311 SQW01 done calling COM method
00:00:12.474330 SQW01 convert COM output "next" back to caller format
00:00:12.474339 SQW01 createOrFindRefFromComPtr(): returning empty MOR for NULL COM pointer
00:00:12.474345 SQW01 done converting COM output "next" back to caller format
00:00:12.474352 SQW01 – leaving _vbox_IVirtualBoxErrorInfo_USCOREgetNext, rc: 0x0 (0)
00:00:15.022175 main Pumping COM event queue
00:00:15.022792 Watchdog Watchdog: checking 1 sessions
00:00:15.022810 Watchdog Watchdog: tNow: 1358500186, session timestamp: 1358500183
00:00:15.022818 Watchdog Watchdog: sleeping 5 seconds
00:00:20.022913 Watchdog Watchdog: checking 1 sessions
00:00:20.022936 Watchdog Watchdog: tNow: 1358500191, session timestamp: 1358500183
00:00:20.022945 Watchdog Watchdog: sleeping 5 seconds
00:00:25.023061 Watchdog Watchdog: checking 1 sessions