This is indicative of a VSS failure. Please try the following steps:
1. open an elevated cmd
2. cd C:\Program Files (x86)\Replibit
3. vshadow-(os version).exe -da
4. vshadow-(os version).exe -p c: d: e: (replace drives with the drives you back up).
If snapshot creation succeeds, run a schedule now under the details page of the protected system.
If snapshot creation fails, check your event logs for vss errors. If vss errors are occurring please try the following:
1. Do a "vssadmin list writers" and ensure all writers are in a stable state.
2. run a chkdsk in read-only mode on each individual volume.
3. preform a "sfc /scannow" in command prompt