qubes-doc/user/troubleshooting/vm-troubleshooting.rst

====================
Qube troubleshooting
====================


VM Kernel troubleshooting
-------------------------


This troubleshoot applies to the non-default kernel choice described in
the :ref:`Managing VM docs <user/advanced-topics/managing-vm-kernels:using kernel installed in the vm>`.

In case of problems, you can access the VM console using
``qvm-console-dispvm VMNAME`` in dom0, then access the GRUB menu. You
need to call it just after starting the VM (until ``GRUB_TIMEOUT``
expires); for example, in a separate dom0 terminal window.

In any case you can later access the VM’s logs (especially the VM
console log ``/var/log/xen/console/guest-VMNAME.log``).

You can always set the kernel back to some dom0-provided value to fix a
VM kernel installation.

Qubes starts, but no VMs load
-----------------------------


First, try to start a particular VM, check any failure message and
direct further steps based on that.

This issue has been seen to occur if a dom0 update is interrupted
halfway through and/or a hard power off is done without shutting down
Qubes, which results in files getting corrupted.

Can not uninstall a VM / "ERROR: VM installed by package manager: template-vm-name"
-----------------------------------------------------------------------------------


All of the following commands should be executed in a dom0 terminal.

When a template is marked as ‘installed by package manager’, but cannot
be uninstalled there, trying to uninstall manually will result in the
error “ERROR: VM installed by package manager: template-vm-name”. Do as
follows to be able to uninstall the template:

1. Check the state of ``installed_by_rpm``

   .. code:: bash

         $ qvm-prefs template-vm-name



2. If ``installed_by_rpm - True``, mark the template as not installed by
   package manager

   .. code:: bash

         $ qvm-prefs template-vm-name installed_by_rpm false



3. Re-check the state of ``installed_by_rpm``



- If ``installed_by_rpm - False``, remove the template like you would a
  regular qube:

  .. code:: bash

        $ qvm-remove template-vm-name



- If ``installed_by_rpm`` remains ``True``, reboot your computer to
  bring qubes.xml in sync with qubesd, and try again to remove the
  template.



Fixing package installation errors
----------------------------------


By default, templates in 4.0 only have a loopback interface.

Some packages will throw an error on installation in this situation. For
example, Samba expects to be configured using a network interface post
installation.

One solution is to add a dummy interface to allow the package to install
correctly:

.. code:: bash

      ip link add d0 type dummy
      ip addr add 192.168.0.1/24 dev d0
      ip link set d0 up



"Cannot connect to qrexec agent" error
--------------------------------------


If you face this error when starting a VM, look into the VM logs at
``/var/log/xen/console/guest-VMNAME.log``. Common reasons that may be
revealed are: too low memory, corrupted files or a VM crash on startup.

If the error occurs as a result of too little initial memory, increase
the initial memory from 200MB to 400MB by navigating to VM settings »
Advanced » Initial memory.

"No match found" when trying to install a template
--------------------------------------------------


For example:

.. code:: bash

      [user@dom0 ~]$ sudo qubes-dom0-update --enablerepo=qubes-templates-itl qubes-template-debian-10
      Using sys-whonix as UpdateVM to download updates for Dom0; this may take some time...
      No Match for argument qubes-template-debian-10
      Nothing to download


This normally means you already have the template installed. It may be
that you have the matching package installed, but you removed or renamed
the template. Check ``rpm -q qubes-template-<name>``. If it lists the
package, but you don’t really have the template present (``qvm-ls``
doesn’t list it), you need to clean up leftovers of the package with
``rpm -e --noscripts qubes-template-<name>``, then install it normally.