Windows Application Event log contains Event ID 8193 and Event ID 12293.
Insufficient space allocated for shadow copy or shadow storage not set.
In order to check that the volume has enough space for the shadow copy, create a shadow copy using the tools integrated in Windows and make sure the shadow copy is created successfully. If required, move the shadow storage to another volume or free up space on the volume.
Select type of the operating system that is being used: Server OS or Workstation OS.
If the volume that you back up has enough free space to store the snapshots, you can resize the shadow storage with the vssadmin resize shadowstorage command. See also Microsoft TechNet: Vssadmin resize shadowstorage.
vssadmin resize shadowstorage /for=c: /on=c: /maxsize=20GB
(!) If you would like to allocate all of the volume's free space for the storage, use the unbounded value. E.g. vssadmin resize shadowstorage /for=c: /on=c: /maxsize=unbounded