This error typically occurs under the following circumstances:

1. The client is unable to connect to the BDR Server backup port (default 32004).

2. VembuBDR services are not running on the server machine.

3. The backup port (32004) is already in use by another application.

To resolve this issue, please follow the steps outlined below:

Step 1: Confirm whether the client can connect to the Backup Server Backup Port (default 32004) by executing the following command in the VembuBDR Client system through the command prompt:

telnet <Server Name/IP Address> <Backup Port>

Example:

telnet 10.x.x.x 32004

Step 2: If the telnet command does not work, check the firewall configuration of the VembuBDR Server. Ensure that the Backup Port (default 32004) is open for incoming traffic.

Step 3: Verify that the VembuBDR services are running on your VembuBDR Server machine, and the Backup Port is in LISTEN state by executing the following commands in the VembuBDR Backup Server system:

For Windows OS:

netstat -an | find <Backup Port>

For Linux OS:

netstat -an | grep <Backup Port>

Step 4: If the Backup Port is not in the LISTEN state, start the VembuBDR service on the Backup Server.

Step 5: If the Backup Port is in the LISTEN state, but the telnet command fails, ensure that the Backup Port is open in the Backup Server network's NAT/Firewall settings.

Step 6: Confirm that both the backup server and the client are configured with the same Backup Port (default 32004). You can verify this by checking the `/conf/SGConfiguration.conf` file on both the client and server ends.

Note: For more information on NAT/Firewall configurations, refer to the following URL: Nat-firewall-configuration.html