Scheduled backups of vCenter Server fail with error "Failed to dispatch metadata information"

Products

• VMware vCenter Server

Issue/Introduction

After an upgrade of vCenter Server, the scheduled backups from the VAMI interface fail with the VAMI UI showing the error "Failed to dispatch metadata information".

However, manually performed backups from the vCenter appliance's VAMI interface are successful. 

Upon investigating, the SSH connection from the vCenter Server appliance to the backup server is successful. There also appears to be enough disk space available and file permissions are correctly applied to the backup volume and directory.

In the vCenter Server's backup logs at /var/log/vmware/applmgmt/backup.log, the following errors are observed upon failure of a scheduled backup:

2026-02-06T05:04:35.997 [20260206-045904-########] [MainProcess:PID-7###04] [Net::GetPNIDAddrInfo:Net.py:657] INFO: PNID '<vCenterServerFQDN>' is resolved with addresses: ['###.###.###.###']

2026-02-06T05:04:36.141 [20260206-045904-########] [MainProcess:PID-7###04] [Proc::GetProcsStatus:Proc.py:328] ERROR: rc: 1, stderr: Traceback (most recent call last):

  File "/usr/lib/applmgmt/backup_restore/py/vmware/appliance/backup_restore/plugins/../util/Calculate.py", line 58, in <module>

    main(sys.argv[1], sys.argv[2], sys.argv[3])

  File "/usr/lib/applmgmt/backup_restore/py/vmware/appliance/backup_restore/plugins/../util/Calculate.py", line 45, in main

    stdout_obj.write(data)

BrokenPipeError: [Errno 32] Broken pipe

 

Environment

VMware vCenter Server 8.0.3-00700

Cause

The issue is caused by interruption to the multiple connections opened by vCenter Server to the backup appliance.

Resolution

Switch the backup mode for vCenter Server from parallel (which opens multiple connections) to serial (which transfers all data via one connection).

This change can be performed as follows:
- First, take a snapshot of vCenter Server so that any changes can be easily reverted
- Next, perform a manual backup of the vCenter Server and verify it was successful
- SSH into the vCenter Server appliance
- Navigate into the directory /etc/applmgmt/appliance/ as follows:
  # cd /etc/applmgmt/appliance/
- Make a backup copy of the file appliance.conf as follows:
  # cp appliance.conf appliance.conf.bak
- Verify that the fileTransferMode is set to parallel currently as follows:
  # grep fileTransferMode appliance.conf
     "fileTransferMode": "parallel",
- Change it to "serial using the "vi" text editor as follows:
  # vi appliance.conf <- and then modify the mode from "parallel" to "serial" and save the file
- Verify that the change was successful as follows:
   # grep fileTransferMode appliance.conf
     "fileTransferMode": "serial",
- Now restart the appliance management service for the change to take effect as follows:
  # service-control --restart applmgmt

After the change, it's necessary to perform a scheduled backup to ensure it succeeds.

Additional Information

Similar issues documented in other KB articles:
VCSA after upgrade to version 8 is not able to complete backup

'BackupManager encountered an exception. See logs for details' error while backing VC VAMI backup with NFS protocol