vCenter Server Backup Fails with "BackupManager encountered an exception" Due to SMB Connection Limits
searchcancel
vCenter Server Backup Fails with "BackupManager encountered an exception" Due to SMB Connection Limits
book
Article ID: 388022
calendar_today
Updated On: 02-11-2025
Products
VMware vCenter Server
Issue/Introduction
When attempting to perform backups of vCenter Server to an SMB share, the backup process fails with the error message "BackupManager encountered an exception. See logs for details." The backup log shows NT_STATUS_SHARING_VIOLATION errors during the cleanup phase.
Backup process initiates successfully and creates directories
Progress stops at approximately 5% completion
Backup fails with "BackupManager encountered an exception"
Backup logs show NT_STATUS_SHARING_VIOLATION errors
Directory creation succeeds but file transfers fail
Environment
VMware vCenter Server Appliance (vCSA) 8.0 or later
SMB backup target configured
SMB server with connection limits configured
Cause
The issue occurs when the SMB server has insufficient concurrent connection limits configured. vCenter Server backup operations require multiple simultaneous SMB connections to perform various operations including:
Writing backup data
Verifying transfers
Cleanup operations
When connection limits are too restrictive, the backup process cannot obtain the necessary connections to complete all required operations.
Resolution
For Windows SMB Servers:
Check SMB server connection limits:
On the Windows server hosting the SMB share, open the share properties
Navigate to Advanced Sharing
Click Advanced Sharing Options
Look for the connection limit setting
Modify connection limits:
Set the connection limit to allow sufficient simultaneous connections
If unsure of the optimal value, use the default unlimited setting
For Linux SMB Servers:
Check current Samba configuration:
View the Samba configuration file:
cat /etc/samba/smb.conf
Look for the `max connections` parameter in the share definition
Modify connection limits:
Edit the Samba configuration file:
sudo vi /etc/samba/smb.conf
Under the relevant share section, adjust or add:
max connections = 0
Note: 0 means unlimited connections
Restart the Samba service:
sudo systemctl restart smbd
Verify the solution:
Attempt a new backup operation
Monitor the backup progress to ensure completion
Check backup logs for any remaining sharing violations
Additional Information
Related symptoms may include failed cleanup operations and orphaned backup directories
Consider monitoring SMB connection usage during backup operations to determine optimal connection limits
For troubleshooting SMB connectivity issues, use the smbclient test commands: