Description of problem: An invocation "Run selected snapshot" is not operational. Version-Release number of component: virt-manager.noarch 2.2.1-3.fc32 Steps to Reproduce: 1. Create two snapshots; 2. Delete the snapshot created last; 3. Invoke run-operation while the focus is on the snapshot created first. Actual results: 1. Each snapshot has its VM state reported as "Running". 2. As intended, VM current session is kept active after the deletion. 3. Snapshot is no run; Message produced by virt-manager: Error running snapshot 'snapshot1': revert requires force: Target CPU feature count 18 does not match source 19 Traceback (most recent call last): File "/usr/share/virt-manager/virtManager/asyncjob.py", line 75, in cb_wrapper callback(asyncjob, *args, **kwargs) File "/usr/share/virt-manager/virtManager/asyncjob.py", line 111, in tmpcb callback(*args, **kwargs) File "/usr/share/virt-manager/virtManager/object/libvirtobject.py", line 66, in newfn ret = fn(self, *args, **kwargs) File "/usr/share/virt-manager/virtManager/object/domain.py", line 1049, in revert_to_snapshot self._backend.revertToSnapshot(snap.get_backend()) File "/usr/lib64/python3.8/site-packages/libvirt.py", line 2187, in revertToSnapshot if ret == -1: raise libvirtError ('virDomainRevertToSnapshot() failed', dom=self) libvirt.libvirtError: revert requires force: Target CPU feature count 18 does not match source 19 Expected results: 1. A unique snapshot to have its VM state reported as "Running". 3. Invoked operation to be effective.
That is a warning from libvirt. Some time since you created that snapshot, the CPU config it detects for your host has changed. This can happen with microcode updates on the host for example. libvirt is warning that your host CPU does not seem compatible with the host CPU that created the snapshot, and is erroring because it may not work or cause runtime issues. You can 'sudo virsh snapshot-revert $VM $SNAPNAME --force' to force it to work. It may cause runtime issues but if it was due to a microcode update then maybe not. So unfortunately this is a legitimate issue libvirt is warning about AFAIK and not anything specific to virt-manager.
Without your interpretation I wouldn't have been able to guess the meanings. Can you confirm that while a VM has several snapshots and for each of them the VM state is reported as "Running" be the guest running or not, is not an issue.
Having multiple snapshots in running state is completely fine. Yes I agree that the error message is very confusing. Unfortunately memory snapshot compatibility across qemu versions is a very complicated topic.