CobianSoft

I cannot create a VSS snapshot or cannot use Volume Shadow Copies at all. Why?

There are several things that could cause the VSS to fail when creating a snapshot. The main problem could be permissions. The user that is executing the backup must have administrator's or backup privileges to use VSS.

Then the volume that you are trying to snapshot must be supported by the system: It must be a NTFS volume (not FAT or FAT32), local (not on a remote machine) and native (not a TrueCrypt volume or some other emulated volume)

In old versions only (this doesn't apply to Version 11): Cobian Backup is a 32 bit application and, on 64 bit systems it must run under WOW64. This works fine on XP64 or Windows Server 2003 64 because 32 bit programs are allowed to call VSS from WOW64. Vista and Windows Server 2008 don't allow that and VSS must be called as a native 64 bit application, which means that you can't use VSS from Cobian Backup on Vista 64 at this moment.

I had the same problem with a fresh install in Windows 10.
Have you checked that you have installed .NET 3.5 framework?

From the FAQ:

Q: Does Cobian Backup work in Windows 8 and 10?
Yes, it works just fine in Windows 8 and 10. You will need to activate/install the .NET 3.5 framework in order to be able to use Volume Shadow Copies. .NET 3.5 is present on Windows 8 and 10 but not active. In order to activate it just open the Control Panel, Click Programs, Click Turn Windows Features on or off and select the .NET 3.5 framework. Do this before installing the program and everything will be working fine.