Delete Snapshot Task Fails With Error A general system error occurred: Fault cause: vim.fault.GenericVmConfigFault | Failed to fetch disk tree

Products

• VMware vCenter Server
• VMware vSphere ESX 7.x
• VMware vSphere ESX 8.x

Issue/Introduction

• Deleting virtual machine snapshot fails with the generic error on vSphere UI: 

Error:  A general system error occurred: Fault cause: vim.fault.GenericVmConfigFault

 

• Below log snippets might be observed:  
  • vmware.log:

YYYY-MM-DDTHH:MM:SSZ In(05) vmx 258220-auto-5j8t-h5:70047031-aa-18-569e SNAPSHOT: SnapshotGenerateDeleteDisks Failed to fetch disk tree: One of the disks in this virtual machine is already in use by a virtual machine or by a snapshot (21)
YYYY-MM-DDTHH:MM:SSZ In(05) vmx 258220-auto-5j8t-h5:70047031-aa-18-569e SNAPSHOT: SnapshotDeleteNode failed: One of the disks in this virtual machine is already in use by a virtualmachine or by a snapshot (21)

 

• • hostd.log:

YYYY-MM-DDTHH:MM:SSZ info hostd[2100425] [Originator@6876 sub=Libs opID=md9lpiw8-261013-auto-5lee-h5:70047630-a5-53-84ad user=vpxuser:domain.local\Administrator] SNAPSHOT: SnapshotDiskTreeAddFromSnapshot: Trying to add snapshot VM-NAME-Snapshot851.vmsn to disk /vmfs/volumes<datastores>/vm-directory/vm-name.vmdk which already has snapshot VM-NAME-Snapshot850.vmsn.
YYYY-MM-DDTHH:MM:SSZ info hostd[2100425] [Originator@6876 sub=Libs opID=md9lpiw8-261013-auto-5lee-h5:70047630-a5-53-84ad user=vpxuser:domain.local\Administrator] SNAPSHOT: SnapshotGenerateDeleteDisks Failed to fetch disk tree: One of the disks in this virtual machine is already in use by a virtual machine or by a snapshot (21)

Environment

VMware vSphere ESXi 7.x

VMware vSphere ESXi 8.x

Cause

The vim.fault.GenericVmConfigFault error when deleting a snapshot often stems from an incorrect hierarchy in the virtual machine's .vmsd file. This file, which stores snapshot metadata, may fail to correctly associate with one or more snapshots present on the virtual machine, leading to configuration errors during snapshot operations.

 

Example of Incorrect .vmsd File Hierarchy:

[root@esxi2:/vmfs/volumes/<datastore_uuid>/ubuntu] cat *.vmsd
.encoding = "UTF-8"
snapshot.lastUID = "7"
snapshot.current = "7"
snapshot0.uid = "5"
snapshot0.filename = "ubuntu-Snapshot5.vmsn"
snapshot0.displayName = "VM Snapshot DATE, TIME"
snapshot0.createTimeHigh = "408330"
snapshot0.createTimeLow = "-206508375"
snapshot0.numDisks = "3"
snapshot0.disk0.fileName = "ubuntu.vmdk"
snapshot0.disk0.node = "scsi0:0"
snapshot0.disk1.fileName = "ubuntu_1.vmdk"
snapshot0.disk1.node = "scsi0:1"
snapshot0.disk2.fileName = "ubuntu_2.vmdk"
snapshot0.disk2.node = "scsi0:2"
snapshot.numSnapshots = "3"
snapshot1.uid = "6"
snapshot1.filename = "ubuntu-Snapshot6.vmsn"
snapshot1.parent = "5"
snapshot1.displayName = "VM Snapshot DATE, TIME"
snapshot1.createTimeHigh = "408330"
snapshot1.createTimeLow = "-200076526"
snapshot1.numDisks = "3"
snapshot1.disk0.fileName = "ubuntu.vmdk"     <<< snapshot1.disk0.fileName should be pointing to ubuntu-000001.vmdk instead of ubuntu.vmdk ,and the same applies to the other disks as well>>>
snapshot1.disk0.node = "scsi0:0"
snapshot1.disk1.fileName = "ubuntu_1.vmdk"
snapshot1.disk1.node = "scsi0:1"
snapshot1.disk2.fileName = "ubuntu_2.vmdk"
snapshot1.disk2.node = "scsi0:2"
snapshot2.uid = "7"
snapshot2.filename = "ubuntu-Snapshot7.vmsn"
snapshot2.parent = "6"
snapshot2.displayName = "VM Snapshot DATE, TIME"
snapshot2.createTimeHigh = "408330"
snapshot2.createTimeLow = "-191878359"
snapshot2.numDisks = "3"
snapshot2.disk0.fileName = "ubuntu-000002.vmdk"
snapshot2.disk0.node = "scsi0:0"
snapshot2.disk1.fileName = "ubuntu_1-000002.vmdk"
snapshot2.disk1.node = "scsi0:1"
snapshot2.disk2.fileName = "ubuntu_2-000002.vmdk"
snapshot2.disk2.node = "scsi0:2"

Resolution

To resolve the issue, follow the below steps:

• Power off the VM
• Create a backup copy of the .vmsd file.

cp *.vmsd /var/core/

• Verify that all snapshot files are present in the VM directory.
• Edit the .vmsd file to check the snapshot chain, ensuring all snapshots are listed in the correct hierarchy.

vi <file-name>.vmsd

• A healthy vmsd with 3 snapshots should look something like this: 

[root@esxi2:/vmfs/volumes/<datastore-uuid>ubuntu] cat *.vmsd
.encoding = "UTF-8"
snapshot.lastUID = "7"
snapshot.current = "7"
snapshot0.uid = "5"
snapshot0.filename = "ubuntu-Snapshot5.vmsn"
snapshot0.displayName = "VM Snapshot DATE, TIME"
snapshot0.createTimeHigh = "408330"
snapshot0.createTimeLow = "-206508375"
snapshot0.numDisks = "3"
snapshot0.disk0.fileName = "ubuntu.vmdk"
snapshot0.disk0.node = "scsi0:0"
snapshot0.disk1.fileName = "ubuntu_1.vmdk"
snapshot0.disk1.node = "scsi0:1"
snapshot0.disk2.fileName = "ubuntu_2.vmdk"
snapshot0.disk2.node = "scsi0:2"
snapshot.numSnapshots = "3"
snapshot1.uid = "6"
snapshot1.filename = "ubuntu-Snapshot6.vmsn"
snapshot1.parent = "5"
snapshot1.displayName = "VM Snapshot DATE, TIME"
snapshot1.createTimeHigh = "408330"
snapshot1.createTimeLow = "-200076526"
snapshot1.numDisks = "3"
snapshot1.disk0.fileName = "ubuntu-000001.vmdk"
snapshot1.disk0.node = "scsi0:0"
snapshot1.disk1.fileName = "Bubuntu_1-000001.vmdk"
snapshot1.disk1.node = "scsi0:1"
snapshot1.disk2.fileName = "ubuntu_2-000001.vmdk"
snapshot1.disk2.node = "scsi0:2"
snapshot2.uid = "7"
snapshot2.filename = "ubuntu-Snapshot7.vmsn"
snapshot2.parent = "6"
snapshot2.displayName = "VM Snapshot DATE, TIME"
snapshot2.createTimeHigh = "408330"
snapshot2.createTimeLow = "-191878359"
snapshot2.numDisks = "3"
snapshot2.disk0.fileName = "ubuntu-000002.vmdk"
snapshot2.disk0.node = "scsi0:0"
snapshot2.disk1.fileName = "ubuntu_1-000002.vmdk"
snapshot2.disk1.node = "scsi0:1"
snapshot2.disk2.fileName = "ubuntu_2-000002.vmdk"
snapshot2.disk2.node = "scsi0:2"

 

• Reload the VM after making the changes

vim-cmd vmsvc/getallvms | grep <vm-name> (this command will give the vmID)

vim-cmd vmsvc/reload <vm-id>

• Delete the snapshots.

Additional Information

Refer: Reloading a vmx file without removing the virtual machine from inventory