If you include more than 65 volumes when backing up with one schedule, Exit Code -311 will occur and the backup will fail.
— log excerpt —
06/06/2018 01:33:23.614 VssStart() 06/06/2018 01:33:23.720 Using Common Provider
06/06/2018 01:33:46.523 COM Error(0x80042312): m_pVssObject->AddToSnapshotSet((LPWSTR)volume.c_str(), providerID, &SnapshotID)
06/06/2018 01:33:46.557 [06/05/2018 18:33:46.461] OUTPUT: – Error text: VSS_E_MAXIMUM_NUMBER_OF_VOLUMES_REACHED
The specified volume or remote file share was not added to the shadow copy set.
This is because the maximum number of volumes that can be included in the shadow copy set has been reached.
Set the number of volumes for the backup to included in one schedule to 64 or less.
– ActiveImage Protector 2016 / 2016R2 / 2018 Windows