Creation of Snapshot and vMotion fails

Products

VMware vCenter Server

Issue/Introduction

Symptoms.

Creation of Snapshot and vMotion fails

Verification:

++ VMware.log indicate that the CBT is enable but, unable to create or open the ctk.vmdk files during snapshot creation.

YYYY-MM-DDThh:mm:ss.ms Wa(03) vmx DISKLIB-CTK: ChangeTracker_Mirror: Failed to create CTK file /vmfs/volumes/########-#######-####-############/VM_Name/VM_Name-ctk-mirror.vmdk. YYYY-MM-DDThh:mm:ss.ms In(05) vmx SNAPSHOT: SnapshotPrepareTakeDoneCB: Prepare phase complete (Could not open or create change tracking file). YYYY-MM-DDThh:mm:ss.ms In(05) vmx SnapshotVMXPrepareTakeDoneCB: Prepare phase failed: Could not open or create change tracking file (5). YYYY-MM-DDThh:mm:ss.ms In(05) vmx SnapshotVMXTakeSnapshotComplete: Done with snapshot 'VM Snapshot 8/26/2025, 4:25:23 PM': 0 YYYY-MM-DDThh:mm:ss.ms In(05) vmx SnapshotVMXTakeSnapshotComplete: Snapshot 0 failed: Could not open or create change tracking file (5).

++ Host logs also, indicate that host couldn’t create or open the CBT (Changed Block Tracking) file (*-ctk.vmdk) for one or more disks while taking the snapshot

YYYY-MM-DDThh:mm:ss.ms. In(166) Hostd[2099700]: [Originator@6876 sub=Vmsvc.vm:/vmfs/volumes/########-#######-####-############/VM_Name/VM_Name.vmx opID=<OPID> user=vpxuser:VSPHERE.LOCAL\Administrator] State Transition (VM_STATE_ON -> VM_STATE_CREATE_SNAPSHOT)
YYYY-MM-DDThh:mm:ss.ms. Db(167) Hostd[2099710]: [Originator@6876 sub=Vigor.Vmsvc.vm:/vmfs/volumes/########-#######-####-############/VM_Name/VM_Name.vmx] Create Snapshot message: An error occurred while saving the snapshot: Could not open or create change tracking file.
YYYY-MM-DDThh:mm:ss.ms. Db(167) Hostd[2099666]: --> An error occurred while taking a snapshot: Could not open or create change tracking file.

Environment

VMware vSphere ESXi 6.x
VMware vSphere ESXi 7.x
VMware vSphere ESXi 8.x

Cause

This issue occurs when the filename-ctk.vmdk file is invalid or out of sync.

Backup products such as VMware vSphere Data Recovery, Veeam, Unitrends, and Commvault take advantage of Changed Block Tracking (CBT) for incremental backups if CBT is enabled in the virtual machine. For more information on CBT, see Changed Block Tracking (CBT) on virtual machines.

The CBT feature of VMware which facilitates taking incremental backups on virtual machines running on VMware ESXi. CBT identifies and tracks block changes since the last backup, and stores these changes as logs for tracking the backups.

Resolution

Steps to Disable CBT:

Power off the virtual machine.
Right-click the virtual machine and click Edit Settings.
Click the Options tab.
Click General under the Advanced section and then click Configuration Parameters. The Configuration Parameters dialog opens.
Set the ctkEnabled parameter to FALSE for the ctkEnabled setting for the VM and for each SCSI disk(s).
Remove the .vmsd file along with any ctk.vmdk files in the VM folder(s). You can create a subfolder and move them there or just delete them.
Power on the virtual machine.