We have a VM in our old ESXi 5.0 environment that has a load of -ctk.vmdk files, some dating back to august last year.
The VM is also complaining about needing a consolidation, however, according to the GUI, there is no snapshots to consolidate, something has got a little confused here.
When we run the consolidation, we get "unable to the access file <unspecified filename> since it is locked".
Rebooting VM is no use, nor powering off and trying that way, still the issue exists. The VMware Data recovery appliance has been rebooted also.
The actual backup routine is successful and is working.
We are using VMware Data recovery appliance, very old school I know...
This sounds like an issue that's related to hot-add backups, that can occur with different backup solutions.
Please check the backup appliance, to see whether it has one of the VM's virtual disks still mounted. If yes, and no backup is currently running, detach/remove that virtual disk from the DR appliance's settings (without checking the Delete from disk option!).
Managed to get round this by rebooting the host, which then allowed us to consolidate the VM and all its files, took a while as there was a lot of ctk.vmdk files. all looks good now though.