Symptoms

You try to install Acronis Cyber Backup 12.5 or Acronis Cyber Protect 15 on a machine where a NIC is disconnected or missing. Both Management Server and Agent are selected for installation.

At 99% of installation progress you get an error:

Registration failed.

Backup agent: "Failed to connect to the management server"

Manual registration fails with an error: ZmqGW return empty AMS addresses list

Cause

Issue in the product.

Backup agent can not be registered on Management Server if the network card (physical or virtual) is not installed or is disabled in the operating system.
In this case, there is no internal loopback traffic between agent and management server via our component Acronis ZeroMQ. While Internet connection is not obligatory, it is required in the current version to have a network adapter enabled in Windows.

Workaround

Enable network adapter temporarily and perform the installation (or registration). For the machines without a physical NIC, a virtual network adapter can be used.