VSS pre-snapshot operations on an Agent may fail almost immediately with "vss script crashed or failed. return code: 1" listed in the Agent log:
ERROR: start_vss_quiesce(remote_agent.pyo:909) policy ihpa_daily, vss failed (reason: vss script crashed or failed. return code: 1), will continue policy anyway
ERROR: pre_snapshot_vss(remote_agent.pyo:713) start_vss_quiesce failed for policy: 2.
The following VSS operations of this backup will also fail immediately with the "Got proc as None" error
ERROR: run_vss_stage_2(worker_functions.pyo:482) Got proc as None for policy PolicyName. returning error.
ERROR: run_vss_stage_3(worker_functions.pyo:571) Got proc as None for policy PolicyName. returning error.
This is usually caused by 3rd party security software blocking CPM Agent from launching VSS scripts.
To verify this, you can check the Windows Application Event Log.
At the time of VSS failures, you may see 3rd party security software errors such as this one:
Error,22/05/2017 2:38:05 AM,McAfee Solidifier,21,None,"McAfee Solidifier prevented unauthorized execution of 'C:\Program Files (x86)\CPM Agent\work\PolicyName_2017-5-22_2_37.bat' (sha1: 16f3eba0a4edde8c5f2be63c33c573f08de2e61e, md5: 7a80c9633b731c1120dc24213547d940, sha256: a1e464052a3e560ab3c7d9e1555943c0fc47455a040d7620babdf0ac485503fc, File Type: script) by process C:\Windows\SysWOW64\cmd.exe (Process Id: 5100, User: NT AUTHORITY\SYSTEM) whose parent is process C:\Program Files (x86)\CPM Agent\CPMAgentService.exe, deny_reason : Local Whitelist - File Not Present (deny reason code: 2) reputation score: 1000"
To resolve this issue, please add the CPM Agent to security software's whitelist.