If you try to make a server backup with Microsoft’s SBS 2011, you will surely get an instant error saying:

“A Volume Shadow Copy Service operation error has occurred: (0x800423f0). The shadow-copy set only contains only a subset of the volumes needed to correctly backup the selected components of the writer”

This can be solved by opening a command-line as administrator and going into the folder:

C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\BIN

and running:

PSConfig.exe -cmd upgrade -inplace b2b -force -cmd applicationcontent -install -cmd installfeatures

After completing, the backup will work like a charm.

Click here to read more on the matter.