Error messages
Message logs in the Management Console of the Backup & Disaster Recovery appliance show the following error:
VSS Snapshot Creation failed. Check Log file for more details.
Error description
The VSS failure you see is due to insufficient storage space available to create the VSS snapshot.
The actual error message in the trace file is the following:
VSS_E_INSUFFICIENT_STORAGE
Steps to resolve
Run systeminfo
from the Support tab, and you can see the available resources for the server.
If this is a VM, you may be able to allocate more system resources to that server and get away from the error.
See Microsoft knowledge base article for details.