RHV VMs fails to start due to "failed to initialize spice server" error

Issue

RHV VMs fails to start with following error in the vdsm.log

2020-07-23 12:53:12,118+0000 ERROR (vm/155feee6) [virt.vm] (vmId='178fabc6-177a-47c6-a9ec-31b66367680b') The vm start process failed (vm:934)
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/vdsm/virt/vm.py", line 868, in _startUnderlyingVm
    self._run()
  File "/usr/lib/python2.7/site-packages/vdsm/virt/vm.py", line 2895, in _run
    dom.createWithFlags(flags)
  File "/usr/lib/python2.7/site-packages/vdsm/common/libvirtconnection.py", line 131, in wrapper
    ret = f(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/vdsm/common/function.py", line 94, in wrapper
    return func(inst, *args, **kwargs)
  File "/usr/lib64/python2.7/site-packages/libvirt.py", line 1110, in createWithFlags
    if ret == -1: raise libvirtError ('virDomainCreateWithFlags() failed', dom=self)
libvirtError: internal error: qemu unexpectedly closed the monitor: 2020-07-16T13:53:10.915172Z qemu-kvm: -drive file=/var/run/vdsm/storage/efe129a4-6084-47d8-8c76-9e017ac504eb/73b63204-540c-412a-a3bd-ec08b1ee2ecb/9168ae3b-330a-4c7c-be13-7185c819b1bb,format=raw,if=none,id=drive-ua-73b63204-540c-412a-a3bd-ec08b1ee2ecb,serial=73b63204-540c-412a-a3bd-ec08b1ee2ecb,werror=stop,rerror=stop,cache=none,aio=threads: 'serial' is deprecated, please use the corresponding option of '-device' instead
(process:59895): Spice-WARNING **: 13:53:10.926: reds.c:2977:reds_init_ssl: Could not use private key file
2020-07-16T13:53:10.926393Z qemu-kvm: failed to initialize spice server