Volume Shadow Copy Service error: Unexpected error DeviceIoControl hr = 0x80070005, Access is denied

Hello Guys,

Recently I've noticed an failing DPM job in SC DPM 2012 R2. In Event Viewer | Application I found the following error related to VSS

Volume Shadow Copy Service error: Unexpected error DeviceIoControl(\\?\Volume{e6ac2b07-7600-11e3-9414-00155d021409} - 0000000000000164,0x0053c06c,000000BAC9E6A780,0,000000BAC9E69770,4096,[0]).  hr = 0x80070005, Access is denied.
. 

Operation:
   Query diff area for this volume

Context:
   Volume Name: \\?\Volume{e6ac2b07-7600-11e3-9414-00155d021409}\

I mounted the volume and run chkdsk /f /r  then retried backup job and error persist.

vssadmin list shadowstorage gives 

Error: The shadow copy provider had an error. Please see the system and
application event logs for more information.

vssadmin list writers gives 

  State: [1] Stable
  Last error: No error

for all writers.

Please advise

Thanks,

Andrei

Andrei Moraru Endava