1. You installed Acronis Backup 12.5 Update 4 (build 12730 and higher),
2. When you try to create a new backup plan or apply existing plan to a device, operation fails with the following error message
Failed to connect to 127.0.0.1 port 30667: Connection refused
Issue in the product.
This issue has been fixed in Acronis Backup 12.5 Build 13400, please update to the latest build.
To work around the issue without updating disable IPv6: see Guidance for configuring IPv6 in Windows for advanced users and restart Acronis services.