Problem Description
The backup of a VMware virtual machine (VM) fails during snapshot creation with the following error:
VMWARE_VMOMI65535 - Unable to communicate with the remote host.
Traceback
The backup job fails while creating a VMware snapshot.
The detailed job logs contain entries similar to the following:
[INFO] Taking Snapshot... [INFO] Waiting for tasks to complete [ERROR] SyncError: Unable to communicate with the remote host, since it is disconnected. msg = 'Unable to communicate with the remote host, since it is disconnected.' [ERROR] Error <class 'inSyncLib.inSyncError.SyncError'>: Unable to communicate with the remote host, since it is disconnected. (#10006ffff : vmodl.fault.HostNotConnected) (Error Code : VMWARE_VMOMI65535)
The detailed job logs are available at:
C:\ProgramData\Druva\EnterpriseWorkloads\Vmware\Backup\<Backupset>\<Job_ID>
Cause
This error indicates that Druva is unable to communicate with the ESXi host that is managing the virtual machine during snapshot creation.
The issue can occur due to one or more of the following reasons:
The backup proxy is disconnected or unavailable.
The ESXi host is disconnected from vCenter.
Network connectivity issues between the backup proxy and the ESXi host (TCP port 902).
The ESXi host is not licensed for VMware vStorage APIs (VADP).
vCenter credentials configured in Druva are outdated or incorrect.
Special character encoding conflicts during VMOMI/VDDK calls.
Resolution
Perform the following verification and troubleshooting steps.
1. Verify the Backup Proxy Status
Ensure that the VMware backup proxy is online and in a Connected state in the Druva Management Console.
2. Verify the ESXi Host Status
In the VMware vSphere Client, confirm that the virtual machine is not hosted on an ESXi server showing a Disconnected state.
If the ESXi host is disconnected, reconnect it to vCenter before retrying the backup.
3. Verify Network Connectivity
Ensure that the backup proxy can communicate with the ESXi host over TCP port 902.
Run the following command from the backup proxy:
telnet <ESXi_IP_or_Hostname> 902If the connection fails, verify that firewalls, network ACLs, or security appliances are not blocking communication on port 902.
4. Verify VMware Licensing
Ensure that the ESXi host is licensed for VMware vStorage APIs (VADP), which are required for image-level backups.
To verify the license:
Open the vSphere Web Client.
Navigate to Administration > Licensing.
Select the Licenses tab.
Select the assigned license.
Click View License Key and verify that the installed edition supports vStorage APIs.
Special character encoding conflicts during VMOMI/VDDK calls.
5. Verify vCenter Credentials
Check whether the vCenter credentials have recently been changed in the VMware environment.
If the credentials have been updated, ensure that the same credentials are also updated in the Druva Management Console. Incorrect or expired credentials can prevent the backup proxy from communicating with vCenter and ESXi hosts.
6. Check VM and Datastore Configuration (Special Characters)
Backup or snapshot failures can occur if object names contain special characters that interfere with API or VDDK path resolution.
Verify Object Names:Ensure that the Virtual Machine name, Datastore name, Cluster, and Folder paths do not contain unsupported special characters (e.g., `%`, `#`, `@`, `&`, `\`, `/`).
Rename & Retry: If special characters are present, rename the affected VM or Datastore in vCenter and re-run the backup job.