Error: Live migration of 'Virtual Machine WIN2012-STD' failed. Virtual machine migration operation for 'WIN2012' failed at migration source 'WIN2012-R2-A'. The Virtual Machine Management Service failed to establish a connection for a Virtual Machine migration with host 'WIN2012-R2-B': The specified target is unknown or unreachable (0x80090303).
The Virtual Machine Management Service failed to authenticate the connection for a Virtual Machine migration at the source host: The specified target is unknown or unreachable (0x80090303).
Cause: The Service Principal Name (SPN) for the remote computer name does not exist and/or it is not added as constrained delegation for Kerberos.
Resolution:
1. Open the Active Directory Users and Computers snap-in.
2. From the Computers folder, right-click the computer account of the source server and then click Properties.
3. In the Properties dialog box, click the Delegation tab.
4. On the delegation tab, select Trust this computer for delegation to the specified services only. Under that option, select Use Kerberos only.
6. Click Add.
7. In the Add Services dialog box, click Users or Computers.
8. In the Select Users or Computers dialog box, type the name of the destination server [WIN2012-R2B].
9. Repeate save steps for another server.
10. on each server execute next list:
setspn -S "Hyper-V Replica Service/WIN2012-R2A" WIN2012-R2A
setspn -S "Hyper-V Replica Service/WIN2012-R2A.domain.local" WIN2012-R2A
setspn -S "Microsoft Virtual Console Service/WIN2012-R2A" WIN2012-R2A
setspn -S "Microsoft Virtual Console Service/WIN2012-R2A.domain.local" WIN2012-R2A
setspn -S "Microsoft Virtual System Migration Service/WIN2012-R2A" WIN2012-R2A
setspn -S "Microsoft Virtual System Migration Service/WIN2012-R2A.domain.local" WIN2012-R2A
net stop vmms && net start vmms
gpupdate /force