System state failures in pure disk

Hello All,

it was windows 2008 r1 Client backup is failing with system state(completing with 64%), and getting below errors.

Error: 2: resource child process: snapshot required but there is nothing to snap: no such object
Error: 2: name process: unable to process 'Shadow?Copy?Components': no such object

troubleshooting steps:
We have been checked all writers are in stable state, But still backup is failing with system state error.

Kindly let us know what was the next troubleshooting step to proceed from here.

pure disk version is V6.6.4

Thanks.