## TL;DR
When VMware itself reports consolidate snapshots failed, the delta merge is blocked by a lock, a mounted delta on a backup proxy, or thin datastore headroom. Check the VM file locks, remove the disk from any proxy still holding it, confirm space, and run consolidation from vCenter during a quiet period while watching the task rather than cancelling it.

```text
vmware "consolidate snapshots" failed
```

## Use this when
- vCenter shows consolidate snapshots failed or a consolidation needed warning that will not clear.
- Backup jobs for the VM warn about snapshot state every night.
- One or more delta files keep growing between backups.

## Not for this skill when
- Veeam cannot create the snapshot initially. That happens before consolidation.
- A parent VMDK is deleted and the chain is broken. That needs chain repair or restore.

## Steps
1. In vCenter, open the failed consolidation task details and record its exact error. Verify: the hypervisor error text is captured
2. Check whether the VM disks are still attached to a backup proxy VM and remove them there if present. Verify: no proxy holds the VM disks
3. Confirm datastore free space exceeds the largest delta size and check for other space consumers. Verify: space is sufficient for the merge
4. Start consolidation from vCenter during low I/O and monitor to completion without cancelling. Verify: the task completes and deltas merge
5. Take a fresh backup and confirm the snapshot is created and removed cleanly. Verify: no consolidation warning returns

## Variant phrasings
### vsphere consolidate snapshots failed lock
The lock phrasing.
### vmware snapshot consolidation needed wont clear
The warning variant.
### esxi consolidate failed datastore space
The space wording.

Compatibility: VMware vSphere and ESXi 7 and 8 with vCenter, VMFS and vSAN datastores, with or without Veeam in the backup path.

## Why it happens
Consolidation is a background merge that competes with the running VM for file locks and I/O. Backup architectures that hot-add disks to proxies can leave those disks attached after a failed job, and the merge then cannot get exclusive access. Datastore pressure makes it worse because VMFS needs working room proportional to delta size.

## Edge cases / pitfalls
- A VM with a delta older than a few days is a risk, not just a warning. Escalate by age.
- vSAN consolidation failures can implicate component health. Check vSAN health alongside file locks.
- Taking a new snapshot and deleting all snapshots sometimes clears what plain consolidation cannot, but only with space headroom.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_tRIHGnS0pM5U_p91xDYsyw