SMB backups fail in vCenter Server with 'com.vmware.applmgmt.backup.plugin.timeout' error
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SMB backups fail in vCenter Server with 'com.vmware.applmgmt.backup.plugin.timeout' error

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Article ID: 315214

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Updated On:

Products

VMware vCenter Server

Issue/Introduction

When attempting a file-based backup of the vCenter Server Appliance (vCSA) using the SMB protocol, the backup job fails.
 
The backup progress times out in the vCenter Server Appliance Management Interface (VAMI).

In the /var/log/vmware/applmgmt/backup.log file, you see error entries indicating an smbclient timeout and plugin error code 7:
 
YYYY-MM-DDT HH:MM:SS UTC [17083]INFO:plugins.SMBClientStorageIOLib:Running Command: ['/usr/bin/smbclient', '//<Backup_Server_FQDN>/<Backup_Share>/', '-A', '/dev/shm/smbCredentialFile######', '--send-buffer', '100M', '-c', 'cd NAME/; ls']
YYYY-MM-DDT HH:MM:SS UTC [17083]ERROR:plugins.SMBClientStorageIOLib:Timeout while running command
YYYY-MM-DDT HH:MM:SS UTC [17083]ERROR:vmware.appliance.vapi.impl:pint.Error('com.vmware.applmgmt.backup.plugin.timeout', 'Operation timed out.', **{'args': ['Plugin error occurred. ErrCode: 7, Args: ()']})

Environment

VMware vCenter Server 7.0.x

VMware vCenter Server 8.0.x

Cause

This issue occurs when the backup server's Fully Qualified Domain Name (FQDN) resolves to multiple IP addresses (such as in a multi-homed storage environment or a round-robin DNS configuration).

When resolving the FQDN, the underlying SMB client (smbclient) may attempt to connect via the first IP address returned by the DNS server. If that specific IP address is blocked by firewall rules, network segmentation, or is otherwise inaccessible to the vCenter Server, the connection fails. This results in an NT_STATUS_BAD_NETWORK_NAME or a command timeout (ErrCode: 7) because the client cannot establish a stable path to the share.

Resolution

To resolve this issue, modify the vCenter backup configuration to target the backup server using a direct, routable IP address instead of its FQDN.

Follow these steps to update your configuration:

  1. Log into the vCenter Server Appliance Management Interface (VAMI) via https://<vCenter_FQDN>:5480 using root credentials.

  2. Navigate to the Backup panel section in the left-hand navigation menu.

  3. Locate your scheduled backup profile, select it, and click Edit.

  4. In the Backup Location step of the wizard, locate the location URI textbox.

  5. Modify the existing path structure to utilize a direct IP string instead of a domain name.

    • Example FQDN Path: smb://backup-server.domain.local/<Backup_Share_Path>

    • Modified IP Path: smb://##.###.##.##/<Backup_Share_Path>

  6. Progress through the remaining wizard steps to save and record the modified backup specification.

  7. Verify remediation status by performing an immediate manual backup invocation by clicking Backup Now.

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