VM Backup Failures Due to Network Communication Breakdown Between vCenter Server and Backup Proxy VM

Products

• VMware vCenter Server

Issue/Introduction

^{This article documents a recurring issue in vSphere environments where virtual machine (VM) backup jobs fail consistently. A network communication between the vCenter Server and the Backup Proxy VM which is a critical component for successful backup operations.}

^{Administrators may notice repeated backup job failures accompanied by errors indicating connectivity or communication issues between these components.}

Environment

• ^{VMware vCenter Server 7.x, 8.x}
• ^{Third-party or native backup solution integrated with vCenter Server}

Cause

^{Due to Backup Proxy VM was unable to establish the required data and control channels with the vCenter Server. This communication failure prevented the backup engine from initiating and completing VM snapshot and data transfer operations.}

Resolution

^{Recommended Actions:}

          ^{1. Engage Your Network Team}

                  ^{Initiate a review of the physical and virtual network paths between the vCenter Server and the Backup Proxy VM.}

                  ^{Validate that both systems reside on routable subnets and that no VLAN segmentation, ACLs, or switch-level configurations are blocking traffic.}

          ^{2. Verify Port Accessibility}

                  ^{Ensure that required ports for backup communication are open and reachable in both directions.}

          ^{3.  Perform Connectivity Tests}

                  ^{Use tools such as ping, telnet, or curl to confirm bidirectional communication between the vCenter Server and the Backup Proxy VM.}

Additional Information

^{Successful VM backups rely on seamless communication between the vCenter Server and the Backup Proxy VM. Any disruption at the network layer can prevent snapshot coordination, data transfer, and job completion. Addressing the connectivity issue restores the backup workflow and ensures data protection continuity.}

^{For further technical guidance, refer to the official Broadcom documentation: 🔗 https://techdocs.broadcom.com/us/en/vmware-cis/vsphere/vsphere-sdks-tools/8-0/virtual-disk-development-kit-programming-guide/backing-up-virtual-disks-in-vsphere/design-and-implementation-overview/communicating-with-the-server.html}