VM Backup fail: vim.fault.invalid snapshot format

Hi everybody,

I have a problem from few days: backup of my VM fails with this error:

error 'VmProv' opID=SWI-50d9680c-b9 [Workflow] Get exception while executing action vpx.vmprov.CreateSnapshot: vim.fault.InvalidSnapshotFormat

VM doesn't have any snapshot. In the VM directory there is a vmx.lck file (0 Kb): is possible is this file the problem? there isn't any other vmx file, so I can't see the configuration of VM.

Can anybody help me?

thanks

Simone