Failed talking to pod: 'NoneType' object has no attribute 'id' error

I am seeing this error when trying to add new POD (virsh type) to MAAS 2.5.1

POD is running Xenial and following libvirt version.

root@maas-pods:~# dpkg -l | grep libvirt
ii libvirt-bin 1.3.1-1ubuntu10.24 amd64 programs for the libvirt library
ii libvirt0:amd64 1.3.1-1ubuntu10.24 amd64 library for interfacing with different virtualization systems
ii python-libvirt 1.3.1-1ubuntu1.1 amd64 libvirt Python bindings

I found that culprit here is one of the VM that has connected block storage that is not a part of libvirt pool.

root@maas-pods:~# virsh domblklist ubuntu18.04
Target Source
------------------------------------------------
vda /dev/libvirt/lvol0

Because /dev/libvirt/lvol0 was not a part of any defined libvirt pools MAAS is unable to add POD.

To solve this issue I have created (defined) libvirt pool that pointed to LVM volume group that held block device of running VM.

cat > /tmp/libvirt.xml <<EOL
<pool type='logical'>
  <name>libvirt</name>
  <uuid>d82c0b30-c0bf-45e6-9d0f-b1504f753ebc</uuid>
  <source>
    <device path='/dev/vdd'/>
    <name>libvirt</name>
    <format type='lvm2'/>
  </source>
  <target>
    <path>/dev/libvirt</path>
  </target>
</pool>
EOL

virsh pool-define /tmp/libvirt.xml
virsh pool-start libvirt

Once libvirt has been aware of existing LVM volume group I re-tried to add POD in MAAS UI and this time it was successful.