This issue may occur if you reinstall vCenter Server or move to another vCenter Server and a virtual machine uses a distributed virtual switch that does not exist in the new vCenter Server.
To resolve this issue, ensure that the virtual machine is configured to use an existing network label.
To ensure that the virtual machine is configured to use an existing network label:
- Right-click the virtual machine and click Edit Settings.
- Select the network adapter and choose an existing network label.