Migration error: Customer.Client.Network.SyncConnectFailed

Problem description

During an SMC migration, the migration task reports the error "Customer.Client.Network.SyncConnectFailed".

Causes

The SMC client on the source server cannot connect to the network for data synchronization. Possible causes:

• The data synchronization port (port 8703) on the destination instance is not working correctly.

• The source server cannot access port IP:8703 on the destination instance.

Solutions

1. Verify that port 8703 on the destination instance is accessible.

   1. Go to the ECS console - Instances page.

   2. In the upper-left corner of the page, select the resource group and region where the destination instance is located.

   3. Confirm that the destination instance is in the Running state.

      • If the instance is running, proceed to the next step.

      • If the instance is stopped, start the instance and then proceed to the next step.

      • If the instance is released, create a new migration task. For more information, see Migrate a server to an ECS instance.

   4. Click the ID of the destination instance to go to the instance details page. On the Remote Commands / Files tab, click Send Remote Commands.

      • For Windows: In the Command field, enter netstat -ano | findstr 8703 and click Run.

      • For Linux: In the Command field, enter netstat -ano | grep 8703 and click Run.

      If the command succeeds and returns output related to port 8703, the port is working correctly on the destination instance.

   5. Verify that port 8703 is allowed in the inbound rules of the security group for the destination instance and that no conflicting rules block access.

      Note

      By default, an SMC migration task automatically associates a temporary security group with the destination instance. This security group allows inbound traffic on port 8703.

2. Verify that the network services on the source server are working correctly.

   1. Verify that local network services on the server are working correctly, including hosts and DNS configurations.

   2. By default, the migration task uses the public mode for transmission. Ensure that the source server can access the Internet.

   3. If you selected the private mode for the migration task, ensure that a private connection is established from the source server to the destination VPC or vSwitch. For more information, see Private network migration.

      Note

      If you are unsure whether a private connection is established, select the public mode for transmission. If you selected the private mode by mistake, select the public mode and try again.

3. Verify network connectivity from the source server to the destination instance.

   1. Allow the ICMP protocol in the inbound rules of the security group for the destination instance. Use the ping command to test the network connectivity from the source server to the destination instance.

      If the ping fails, troubleshoot the on-premises network configuration or intermediate network devices, such as firewalls or proxies, to check for outbound IP access restrictions.

   2. Use the telnet command to test the connectivity to port 8703 on the destination instance. If the connection fails, troubleshoot the on-premises network configuration or intermediate network devices, such as firewalls or proxies, to check for outbound IP and port access restrictions.

   3. Check whether Alibaba Cloud Firewall is enabled with an access control policy that blocks network access, such as Internet firewalls or VPC firewalls. For more information, see Internet firewall.

   4. If the migration task uses the public mode and the transmission mode is block replication, Secure Sockets Layer (SSL) encryption is used for secure data transmission by default. If the source server does not support or restricts the use of SSL, use the Modify Migration Job feature to disable SSL-Encrypted Transmission.

4. After you resolve the issue, run the SMC client to verify the fix.