"Could not open or create change tracking file" error during Snapshot creation, snapshot deletion, or vMotion
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"Could not open or create change tracking file" error during Snapshot creation, snapshot deletion, or vMotion

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Article ID: 408791

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Updated On:

Products

VMware vCenter Server

Issue/Introduction

When attempting to execute standard virtual machine operations such as snapshot creation, snapshot deletion (consolidation), or storage vMotion, the operation fails and rolls back.

The task wizard inside vSphere Client generates a variation of the following message:

An error occurred while saving the snapshot: Could not open or create change tracking file.

Reviewing the primary diagnostics log files exposes targeted behavioral exceptions:

  1. Inside the Virtual Machine Log (vmware.log):

The virtual machine context flags an explicit subsystem initialization block where the virtual machine monitor (vmx) cannot provision the internal change tracking logic device:

DISKLIB-CTK: ChangeTracker_Mirror: Failed to create CTK file /vmfs/volumes/########-#######-####-############/VM_Name/VM_Name-ctk-mirror.vmdk.

SNAPSHOT: SnapshotPrepareTakeDoneCB: Prepare phase complete (Could not open or create change tracking file).

SnapshotVMXPrepareTakeDoneCB: Prepare phase failed: Could not open or create change tracking file (5).

SnapshotVMXTakeSnapshotComplete: Done with snapshot 'VM Snapshot 8/26/2025, 4:25:23 PM': 0

SnapshotVMXTakeSnapshotComplete: Snapshot 0 failed: Could not open or create change tracking file (5).

  1. Inside the ESXi Host Management Log (hostd.log):

The virtualization management service registers an invalid state transition during snapshot invocation, tracking the issue back to a failure to touch the configuration descriptor files:

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)

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.

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 a virtual machine's tracking telemetry layer gets desynchronized. Specifically, the Change Block Tracking (CBT) map descriptor file (*-ctk.vmdk) becomes invalid, locked, or structurally corrupt.

External backup applications leverage the native VMware CBT API to perform high-efficiency incremental block tracking by monitoring localized delta changes across virtual storage nodes. When an ESXi host attempts to snapshot or migrate a VM with an out-of-sync or corrupt data index map, the platform protects file integrity by aborting the execution sequence. Since the backup management loop cannot map changes across a damaged tracking table, the hypervisor engine shuts down downstream snapshot processing threads completely.

Resolution

To resolve this issue, the Changed Block Tracking (CBT) mapping table must be cleanly reset. This process removes the out-of-sync data maps and forces the hypervisor to generate brand-new, healthy change tracking tables upon the next initialization sequence.

⚠️ Pre-Execution Note: Resetting CBT will cause your backup application to run a Full Backup during its next scheduled cycle rather than an incremental pass. Plan accordingly based on your environment's storage allocation constraints.

Step-by-Step Triage & Reconstruction Procedure:

  1. Gracefully Power Off the target virtual machine experiencing the snapshot fault.

  2. Log into the vSphere Client interface, navigate to the inventory panel, right-click the VM object, and choose Edit Settings.

  3. Select the VM Options tab at the top of the interface pane.

  4. Expand the Advanced section dropdown, locate the General properties line item, and click on Configuration Parameters... to populate the options parameter list matrix.

  5. Identify the parameter named ctkEnabled and change its value string definition from TRUE to FALSE.

  6. Scan the remaining rows for each distinct virtual disk associated with the VM definition (e.g., scsi0:0.ctkEnabled, scsi0:1.ctkEnabled) and toggle each matching parameter field value to FALSE. Click OK to save the state map changes.

  7. Open a secure terminal line session (SSH) directly to the parent ESXi host or leverage the datastore browser utility window to access the virtual machine's target home storage directory.

  8. Locate and remove the matching tracking elements. As a safe staging practice, it is recommended to create a temporary backup subfolder (e.g., OLD_CTK_HOLD/) within the primary workspace directory and move these files inside instead of execution drops:

       *.vmsd (The parent snapshot tree layout descriptor file)

      *-ctk.vmdk (All binary change block mapping logs for every assigned disk)

  9. Return to your vSphere inventory management workspace and Power On the target virtual machine.

  10. To finalize reconstruction, re-enable the backup interface maps by repeating steps 2-6, transitioning all ctkEnabled field parameter options back to TRUE. Trigger a manual validation snapshot to confirm the Could not open or create change tracking file warning has successfully cleared.

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