I'm having the same problem in Debian Stretch. This might be related to the following bugs: https://bugzilla.redhat.com/show_bug.cgi?id=1397440 https://bugzilla.redhat.com/show_bug.cgi?id=1432684
If you don't need remote connections to my VMs, you can try working around this issue by using a local socket rather than a port:
<graphics type='spice'>
<listen type='socket'/>
<image compression='auto_glz'/>
</graphics>
Thomas
