What were you trying to do that didn't work?

The guest will shut off unexpectedly when snapshot-revert guest to non-file disk status.
In addition, the error message for volume disk is unclear: error: unsupported configuration: cannot generate external snapshot name for disk 'vdb' without source. The error message for block disk seems to be acceptable: error: unsupported configuration: source for disk 'vdb' is not a regular file; refusing to generate external snapshot name.

Please provide the package NVR for which bug is seen:

libvirt-10.0.0-6.el9_4.x86_64
qemu-kvm-8.2.0-11.el9_4.x86_64

How reproducible:

100%

Steps to reproduce

1. Prepare a scsi pool.
# virsh pool-dumpxml iscsi_pool
<pool type='iscsi'>
  <name>iscsi_pool</name>
  <uuid>f9207d17-44ed-43f9-84d1-228afb8a7710</uuid>
  <capacity unit='bytes'>3221225472</capacity>
  <allocation unit='bytes'>3221225472</allocation>
  <available unit='bytes'>0</available>
  <source>
    <host name='127.0.0.1' port='3260'/>
    <device path='iqn.2021-04.com.virtemulated:emulated-iscsi.target'/>
  </source>
  <target>
    <path>/dev/disk/by-path</path>
  </target>
</pool>
# virsh pool-list --all
 Name         State      Autostart
------------------------------------
......
 iscsi_pool   active     no

2. Prepare a running guest with a volume disk.
# virsh dumpxml avocado-vt-vm1 --xpath //disk
......
      <disk type='volume' device='disk'>
        <driver name='qemu' type='qcow2'/>
         <source pool='iscsi_pool' volume='unit:0:0:0' mode='host'/>
        <target dev='vdb' bus='virtio'/>
        <address type='pci' domain='0x0000' bus='0x08' slot='0x00' function='0x0'/>
      </disk>
# virsh list --all
 Id   Name             State
--------------------------------
 4    avocado-vt-vm1   running

3. Create 2 snapshots.
# virsh snapshot-create-as avocado-vt-vm1 snap1 --memspec snapshot=external,file=/tmp/mem.snap1 --diskspec vdb,file=/tmp/test.snap1 --diskspec vda,snapshot=no
Domain snapshot snap1 created
# virsh snapshot-create-as avocado-vt-vm1 snap2 --memspec snapshot=external,file=/tmp/mem.snap2 --diskspec vdb,file=/tmp/test.snap2 --diskspec vda,snapshot=no
Domain snapshot snap2 created
# virsh snapshot-list avocado-vt-vm1
 Name    Creation Time               State
----------------------------------------------
 snap1   2024-03-28 23:29:18 -0400   running
 snap2   2024-03-28 23:29:50 -0400   running

4. Revert snapshot to snap1.
# virsh snapshot-revert avocado-vt-vm1 snap1
error: Failed to revert snapshot snap1
error: unsupported configuration: cannot generate external snapshot name for disk 'vdb' without source
# virsh list --all
 Id   Name             State
---------------------------------
 -    avocado-vt-vm1   shut off

Expected results

Got a clear unsupported configuration clear message and the guest is still running

Actual results

The unsupported configuration error message is not clear and the guest changes to shut off unexpectedly.

Additional info:
avocado-vt-vm1.log: 
2024-03-29 04:30:06.517+0000: 501345: info : virObjectUnref:378 : OBJECT_UNREF: obj=0x7f50b40280e0
char device redirected to /dev/pts/3 (label charserial0)
2024-03-29 04:31:00.213+0000: shutting down, reason=from snapshot