Symptoms

Backup fails with this error:

Socket error 

Cause

Connectivity issue between Agent and Storage Node.

Troubleshooting

1. Using the ping command, check connectivity from Storage Node to Agent machine (by name and by IP):
   ping <hostname>
   ping <IP address>
2. Using the ping command, check connectivity from Agent machine to Storage node (by name and by IP);
3. Make sure that the following ports are open on both Agent and Storage Node, they are required for connectivity: 7780, 9876, 9852, and 9877. This can be tested using telnet command
   
   How to use telnet to test open ports: click to expand

   1) Make sure Telnet client is enabled on the machines:

   Windows 7, 8. 10: go to Control Panel - Programs - Turn Windows features on or off , make sure Telnet component is selected and click OK

   Windows Server 2008: Open “Server Manager” > Features > click “Add Features” > enable “Telnet Client” checkbox > click “Next” > click “Install” > when the feature installation finishes, click “Close”

   Windows Server 2012, 2016: Open “Server Manager” > “Add roles and features” > click “Next” until reaching the “Features” step > tick “Telnet Client” > click “Install” > when the feature installation finishes, click “Close”.

   2) Launch Command Prompt as Administrator on the Agent side: Start -> in search, type cmd -> right-click cmd.exe and select Run as administrator.

   3) Run the following command:

   telnet <machine_name> 9877

   4) Look at the output of the telnet command.

   4.1) If the cmd screen becomes empty, it means that the connection succeeded. 

   4.2) If the output of the telnet command is not an empty black screen, and there are any error messages, it means that the connection is blocked by firewall or other security software.

   Check connection for all required ports

4. Add Acronis Cyber Backup components to the exclusions/white list of your antivirus software: see this article for more information.

Collect information

If the above troubleshooting steps do not help, please collect System information from the affected Agent machine and from machine where Acronis Storage Node is installed and contact Acronis Support.