If you get the error

this is probably because the system did not get a network connection working. This could be for a number of reasons, including bad cabling, connecting the network cable to the wrong interface or driver incompatibility. Make sure your connectivity and drivers are working well with the OS.

After performing the upgrade, the DHCP/DNS server is not functional.

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if you see something like --conf-file=/var/lib/libvirt/dnsmasq/default.conf then you can fix the dnsmasq problem by issuing the following command and then rebooting.

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sudo reboot

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