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

Products

• VMware vCenter Server

Issue/Introduction

Following an upgrade to vCenter Server 8.0U3, scheduled backups initiated from the VAMI interface fail with the error "Failed to dispatch metadata information". Conversely, manual backups performed from the VAMI interface complete successfully.

• The issue is verified by reviewing the /var/log/vmware/applmgmt/backup.log file on the vCenter Server Appliance (VCSA), which contains entries similar to the following:

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

Cause

The issue is caused by an interruption to the multiple concurrent connections opened by the vCenter Server to the backup appliance. The default "parallel" file transfer mode triggers these multiple connections, which are subsequently dropped, resulting in a broken pipe error.

Resolution

Note: A valid snapshot of the vCenter Server Appliance must be taken prior to proceeding, ensuring changes can be safely reverted if necessary.

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

Ensure to have a valid snapshot of vCenter Server Appliance so that any changes can be easily reverted.

1. Log in to the vCenter Server Appliance via SSH/Putty as "root" user
2. Navigate to the configuration directory 

   cd /etc/applmgmt/appliance/
   
   ls -ltrah

3. Create a backup of the existing appliance.conf file: 

   cp appliance.conf appliance.conf.bak

4. Verify that the fileTransferMode is set to "Parallel" you can use "grep" or "less" command to verify:

   grep fileTransferMode appliance.conf
   "fileTransferMode": "parallel",

5. Change it to "Serial" using the "vi" text editor: 

   vi appliance.conf
   
   "fileTransferMode": "serial",

6. Press Esc wq! to save and exit vi editor.
7. Restart the appliance management service for the change to take effect 

   service-control --restart applmgmt

8. After the changes, perform manual backup once first, then proceed to perform a scheduled backup to ensure it succeeds.

 

Additional Information

A similar backup failure scenario is documented in  KB : VCSA after upgrade to version 8 is not able to complete backup

To eliminate potential DNS resolution issues, the IP Address of the SFTP backup target can be configured in place of the FQDN.