Starting up the KVM error occurred

Error starting domain: Requested operation is not valid: network 'default' is not active

Locate the default.xml file

$ locate default.xml
/etc/vic/default/network/default.xml

Review the file

$ cat /etc/vic/default/network/default.xml
<network>
  <name>default</name>
  <uuid>1b9cd3e0-b7f9-4220-97e0-e1b4483ac2d8</uuid>
  <forward mode='nat'/>
  <bridge name='virbr0' stp='on' delay='0'/>
  <mac address='00:16:3e:77:93:c2'/>
  <domain name='default'/>
  <ip address='192.168.122.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.122.2' end='192.168.122.254'/>
    </dhcp>
  </ip>
</network>

Start the default net-starter using virsh

$ sudo virsh net-start default
Network default started

Next start the network using the default

$ sudo virsh net-autostart --network default
Network default marked as autostarted

Everything should be working fine now, KVM starts without error