VSS Errors 1920 and 4350 can be safely ignored
Due to how Windows Update works, Retrospect backup of a Windows volume may show error 1920 or 4350 for many files under:
These errors don’t affect the backup’s validity because affected files are actually inside a Windows disk image (
.VHD) file which does get backed up as a whole by Retrospect.
Last Update: September 8, 2015