When trying to get SVI contents out and vssadmin and diskshadow don’t work, this may:
wmic
(then it its own command prompt) shadowcopy delete
It will require “Y” and “Enter” to be pressed, it will do one at a time. One can also have it delete all noninteractively:
wmic shadowcopy delete /nointeractive
and in Powershell, one can run that noninteractive as a job:
Start-Job -ScriptBlock { wmic shadowcopy delete /nointeractive }