NVP-vProxy: Backups fail "Failing back to the previous backup mode"

Summary: NetWorker VMware Protection (NVP) Virtual Machine (VM) backups fail. The error reported is that the backup failed back to a previous backup mode. This error appears after the backup optimization mode in the policies group was changed. ...

This article applies to This article does not apply to This article is not tied to any specific product. Not all product versions are identified in this article.
Check out other resources

Symptoms

The Backup Optimization mode was changed for the VMware Protection Group. 

The NetWorker VMware Protection integration is configured with the vProxy Appliance. The backups for a VMware Protection group fail indicating the backup mode does not match for the virtual machine (VM). The backup action details and log show: 
MM/DD/YYYY HH:mm:SS [VM_NAME]: Perform incremental backup.
MM/DD/YYYY HH:mm:SS [VM_NAME]: Falling back to the previous backup mode 'VSS'. The configured backup mode 'FSS_8K' does not match the previous mode. Run a full backup to switch the backup mode.
MM/DD/YYYY HH:mm:SS [VM_NAME]: Started backup with job ID '571746' for save-set ID 'e0deff0f-00000006-3f7c58db-5b7c58db-dcc20000-22cafcc9' on vProxy '[VPROXY_NAME]'.
MM/DD/YYYY HH:mm:SS [VM_NAME]: Downloaded vProxy Session log file '/nsr/logs/policy/[POLICY_NAME]/[WORKFLOW_NAME]/571746-[VM_NAME]-YYYY-MM-DD-HH-MM-SS.log' under savejob 571746.
MM/DD/YYYY HH:mm:SS [VM_NAME]: Backup failed.

Cause

The Backup Optimization mode was changed for the VMware Protection Group after performing the initial full level-zero backup. Switching a VM’s backup optimization mode requires a new full (level-zero) backup to serve as the baseline for future backups.

Resolution

Change the backup action configuration to force a full level backup for the new optimization mode. Once the full level backup is complete, the backup action configuration can be changed back to incremental.

Additional Information

Ensure that the Data Domain device has sufficient capacity. During the transition, both backup modes co-exist, doubling storage use until the last Optimized for Capacity backup expires per its retention period. After this, storage consumption will return to normal. 

For further information, see the "vProxy backup optimization modes" section of the NetWorker VMware Integration Guide: https://www.dell.com/support/product-details/product/networker/docs

Affected Products

NetWorker

Products

NetWorker Family
Article Properties
Article Number: 000052960
Article Type: Solution
Last Modified: 14 Aug 2025
Version:  6
Find answers to your questions from other Dell users
Support Services
Check if your device is covered by Support Services.