OS X

Acronis Files Connect versions 10.0.4 and later have been tested for compatibility with macOS 10.12 ‘Sierra’. If you are running an earlier version of Acronis Files Connect, please install 10.0.4 or later to support Sierra client Macs.

In Mac OS X Catalina, Apple introduced a Notarization of software requirement. More details can be read here.

Even though the Backup Agent for MAC should install and function properly on build 12.5.14800 , the OS would still produce a warning that the software could not be checked for malware:

"X can't be opened because Apple cannot check it for malicious software.
This software needs to be updated. Contact the developer for more information."

Symptoms

1) You are trying to install, update, uninstall, register or unregister Agent for Mac.

2) Agent registration on Management Server fails with the error message:

Could not resolve host: localhost; nodename nor servname provided, or not known