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RPC function call failed. The RPC server is unavailable. w/ Application-Aware Image Processing

KB ID: 1174
Product: Veeam Backup & Replication
Version: 5.x, 6.x, 7.x, 8.x, 9.x
Published: 2011-08-23
Last Modified: 2021-01-11
Languages: DE | IT | FR | ES


VSS fails with the error:

RPC error:The RPC server is unavailable. Code: 1722


  1. The ports that Veeam Backup & Replication is attempting to use are blocked by a firewall.
  2. The VeeamVSSSupport service is stuck on the Guest OS
  3. Antivirus or Antimalware software may attempt to interact with the VeeamVSSSupport service executable.

In rarer cases dynamic port allocation needs to be configured.
Note: If the VM that is failing to be connected to is Windows Server 2003, you need to use the RPC Configuration Tool (RPCCfg.exe) from the Windows Server 2003 Resource Kit to complete the process that is described in this article.
Additional troubleshooting steps can be found in the following Microsoft KB article:


Firewall / Ports

A full list of used ports can be found here:

When Veeam Backup & Replication connects to a VM it creates firewall exclusions for the ports and processes it uses. Veeam Backup & Replication however is not able to add firewall exclusions to hardware or third-party software firewalls.

The most common ports that cause this issue when using Application-Aware Image Processing are the Dynamic RPC ports that the temporary guest agents are assigned.

These ports are:

  • 1025 to 5000 (for Microsoft Windows 2003)
  • 49152 to 65535 (for Microsoft Windows 2008 and newer)

Note: The NIC’s Network Location being set to Public mode will also cause this, as Public mode sets the firewall it’s strictest settings.

VeeamVSSSupport service cleanup

When no job is processing the VM connect to it and check the following things:

  1. Make sure the VeeamVSSSupport service is no longer present.
    If it is, use the command ‘sc delete VeeamVSSSupport’ to remove the service.

  2. Make sure the c:\Windows\VeeamVSSSupport folder is not present.
    If it is, delete the folder. If it fails to delete reboot or resolve the file lock.


Please review the full list of Antivirus/Antimalware exclusions listed here:
The most common solution is to exclude the C:\Windows\VeeamVSSSupport\ folder from being scanned.

Dynamic Port Configuration

To configure dynamic port allocation follow the steps outlined in the following Microsoft KB article. These changes will need to be made on the server that Veeam Backup & Replication is having trouble connecting to.

KB ID: 1174
Product: Veeam Backup & Replication
Version: 5.x, 6.x, 7.x, 8.x, 9.x
Published: 2011-08-23
Last Modified: 2021-01-11
Languages: DE | IT | FR | ES

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