Hi
When getting this error; there are several solutions

In my case the destination server had the remote registry service crashed;

following the Veeam forums:

• Make sure the Windows time on the Veeam Backup server is the same as in the guest OS.
• Make sure you do not have a firewall in the way (you can try disabling it for testing).
• Make sure you can connect to the admin share (for example, \\Server Name\admin$) with the same credentials as provided to Veeam Backup &
• Replication for VSS.
• Make sure the VSS writers are set to automatic in the guest OS.
• Make sure you provide Local Administrator (MACHINE\Administrator) or Domain
• Administrator (DOMAIN\Administrator) account privileges.
• Make sure the guest OS is in the same network as the Veeam Backup server.
• Make sure File and Printer Sharing is enabled in the guest OS.
  ​Once File and Printer Sharing is Enabled on the guest OS, ensure to provide permissions through Windows Firewall if applicable
• If the guest OS is Vista/2008 or later:
  In the Network and Sharing Center, verify that it is not set for a public domain.
  Verify that the Remote Registry Service is started.