Today I was tasked with performing a V2V migration of a Windows Server 2016 VM from VMware ESXi 6.5.0 to Windows Hyper-V 2016.
While doing so I was faced with the Error Code: 255 when converting one of the disks,
FAILED: An error occurred during
conversion: 'File-level volume clone error failed with sourcevolume id
44=494?....., and target volume id 44=494?....,. Error code: 225'
The error got resolved by disabling Windows Defender via the Settings app.
Settings > Update & Security > Windows Defender
Set to ‘Off’:
Real-Time protection, Cloud-based Protection, and while you’re at it, Automatic sample submission.
Remember to turn these back on when done.