# Can't start xen VMs

## secretcorporation

I'm getting the following error in virt manager when I try and start my VMs:

  File "/usr/share/virt-manager/virtManager/engine.py", line 588, in run_domain

    vm.startup()

  File "/usr/share/virt-manager/virtManager/domain.py", line 150, in startup

    self._backend.create()

  File "/usr/lib/python2.6/site-packages/libvirt.py", line 300, in create

    if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)

libvirtError: POST operation failed: xend_post: error from xen daemon: (xend.err 'Domain unable to be unpaused: an integer is required')

Does anybody know what that means?

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## snkmoorthy

if you disregard 'libvrt' and use xen-tools(xm) what happens?

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## fbcyborg

Hi!

Same problem here. I can't start hvm guests, since I get this message:

```
Error: Domain unable to be unpaused: an integer is required

Usage: xm start <DomainName>

Start a Xend managed domain

  -p, --paused                   Do not unpause domain after starting it    

  -c, --console_autoconnect      Connect to the console after the domain    

                                 is created

  --vncviewer                    Connect to display via VNC after the       

                                 domain is created

  --vncviewer-autopass           Pass VNC password to viewer via stdin and  

                                 -autopass

```

It seems each guest starts in "paused" status! O_O I don't understand!!

Sometime, I'm not able to start Linux guests as well. 

kernel: xen-sources-2.6.34-r3.

xen 4.0.0

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## fbcyborg

I solved this problem.

The module tun was not loaded when starting the guest domain.

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## idella4

```

an integer is required

```

snkmoorthy is on the right track.

Generally indicates a mis-match between the xen guest and virt-manager and the xen kernel or the xen hypervisor version.  You probably updated xen then once booted into the new hypervisor, attempted to start the vm already listed in virt-manager.

Scrap the guest in virt-manager and start it from scratch.  e.g. Use virt-manager's import mode to re-establish a path for virt-manager to mange and start the vm, or 

```

xm create vm.cfg

```

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## fbcyborg

I trashed virt-manager and all the problems and strange behaviours on my XEN system disappeared.

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## idella4

fbcyborg

yep, that would be a fair summary.  virt-manager is sensitive to changes to the hypervisor.  It's not essential to running vms, as it can be done with xm and virt-viewer and vnc related software.

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## fbcyborg

Just to tell you one of the issues I bumped into, because of virt-manager: each time I was booting a Linux guest OS, the first time gone all right, but the next ones, DHCP client inside the VMs, was stuck while trying to get an IP address. The temporary solution was to perform a xm delete vm_name and xm new vm_name each time before starting the guest again. O_O !

Now that virt-manager is no longer present on my system, all goes pretty well.  :Wink: 

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