I'm connecting to my CentOS 6 libvirtd using virt-manager from my Fedora 14 and I get lots of these in messages: Aug 11 13:51:03 asgard libvirtd: 13:51:03.474: 26145: error : virLibConnError:490 : this function is not supported by the connection driver: virConnectNumOfDefinedInterfaces Aug 11 13:51:04 asgard libvirtd: 13:51:04.475: 14666: error : virLibConnError:490 : this function is not supported by the connection driver: virConnectNumOfInterfaces Aug 11 13:51:04 asgard libvirtd: 13:51:04.478: 313: error : virLibConnError:490 : this function is not supported by the connection driver: virConnectNumOfDefinedInterfaces Aug 11 13:51:05 asgard libvirtd: 13:51:05.477: 14663: error : virLibConnError:490 : this function is not supported by the connection driver: virConnectNumOfInterfaces Aug 11 13:51:05 asgard libvirtd: 13:51:05.480: 14665: error : virLibConnError:490 : this function is not supported by the connection driver: virConnectNumOfDefinedInterfaces Aug 11 13:51:06 asgard libvirtd: 13:51:06.477: 14664: error : virLibConnError:490 : this function is not supported by the connection driver: virConnectNumOfInterfaces Aug 11 13:51:06 asgard libvirtd: 13:51:06.480: 26145: error : virLibConnError:490 : this function is not supported by the connection driver: virConnectNumOfDefinedInterfaces Aug 11 13:51:07 asgard libvirtd: 13:51:07.476: 14666: error : virLibConnError:490 : this function is not supported by the connection driver: virConnectNumOfInterfaces Aug 11 13:51:07 asgard libvirtd: 13:51:07.482: 313: error : virLibConnError:490 : this function is not supported by the connection driver: virConnectNumOfDefinedInterfaces Looking at http://libvirt.org/hvsupport.html, these are not supported over a remote connection until 0.7.2, but spamming messages like this is not sensible. Either libvirtd should shut up about unsupported functions, or virt-manager should be more clever and not try to use unsupported functions.
experiencing the same issue
I believe virt-manager did get more clever about this. If anyone can still reproduce with a recent virt-manager version, please file a new virt-manager bug