vSAN Data Protection unable to clone VMs

Products

• VMware vSAN
• VMware Live Recovery

Issue/Introduction

When trying to do a clone of a VM via vSAN Data Protection you get the following error "User initiated task execution failed."

From the snapservice log the below error is seen:

{"level":"error","timestamp":"2026-01-19T14:21:54.215Z","C":"clusters/virtual_machines.go:722","message":"Error while waiting for CreateChildDisk task","opID":"696d2d25","createChildDiskTask":{"TaskInfo":{"Key":"com.vmware.vsan.snapservice.createchilddisk","Result":{"taskMoId":"session[52ffeb99-8437-0da1-59ad-############]524dee03-7f69-32a8-3f6c-############"},"State":"running","Fault":null}},"error":"A general system error occurred: Invalid change tracker error code","S":"gitlab.###.######.com/core-build/vsan_snapshot_service/pkg/service/clusters.createChildDiskTask\n\t/build/mts/release/bora-24905721/snapservice/pkg/service/clusters/virtual_machines.go:722\ngitlab.###.######.com/core-build/vsan_snapshot_service/pkg/service/clusters.createChildDisks\n\t/build/mts/release/bora-24905721/snapservice/pkg/service/clusters/virtual_machines.go:1108\ngitlab.###.######.com/core-build/vsan_snapshot_service/pkg/service/clusters.LinkedCloneVM\n\t/build/mts/release/bora-24905721/snapservice/pkg/service/clusters/virtual_machines.go:1186\ngitlab.###.######.com/core-build/vsan_snapshot_service/pkg/controller/clusters.VirtualMachinesImpl.LinkedClone.func1\n\t/build/mts/release/bora-24905721/snapservice/pkg/controller/clusters/VirtualMachinesImpl.go:194\ngitlab.###.######.com/core-build/vsan_snapshot_service/pkg/tasks.(*Executor).execute\n\t/build/mts/release/bora-24905721/snapservice/pkg/tasks/executor.go:106\ngitlab.###.######.com/core-build/vsan_snapshot_service/pkg/tasks.(*taskExecutorFunction).Process\n\t/build/mts/release/bora-24905721/snapservice/pkg/tasks/executor.go:90\ngitlab.###.######.com/core-build/vsan_snapshot_service/pkg/service/sync.(*worker).start.func1\n\t/build/mts/release/bora-24905721/snapservice/pkg/service/sync/thread_pool.go:459"}
{"level":"error","timestamp":"2026-01-19T14:21:54.215Z","C":"clusters/virtual_machines.go:1188","message":"Failed to create child disks for base vmdk file","opID":"696d2d25","cluster":"domain-c###","lc vm name":"VMTest-clone","vmdkFilePath":"

Environment

VMware vSAN ESA 8.x

vSAN Data Protection 8.x

Cause

This is an issue with change track blocking (CBT) on the VM snapshots.

Resolution

Broadcom is aware of this issue and planning to fix it in a future version. 

Alternatively disable CBT on VMs being protected by vSAN DP. See KB Changed Block Tracking (CBT) on virtual machines

Workaround:

1. Find the snapshot folder being used for the linked clone on the vSAN datastore
   
   a. Log into the snapservice applaince
   b. Run select * from protection_groups to list all VM snapshot info
   c. The path for the snapshot folder will be labeled namespace
   
   
   
2. Locate all *.vmdk files for the active linked clone snapshots and delete or comment out the line with "changeTrackPath"
3. Modify the VMX file and replace all lines similar to below and replace TRUE with FALSE
          ctkEnabled = "TRUE"
          scsi0:0.ctkEnabled = "TRUE"
      
4. If there is a folder named "baseVMDK", also update the "*.vmdk" files in there to remove the "changeTrackPath" as well

The below commands can help with making the changes to the respective files.

grep changeTrackPath *.vmdk

sed -i 's/changeTrackPath/#changeTrackPath/' *.vmdk

 

grep ctkEnabled *.vmx

sed -i 's/ctkEnabled = "TRUE"/ctkEnabled = "FALSE"/g' *.vmx