The error 40002 could be reported in multiple scenarios of VHD mount and unmount failure.Here are more details -WMI Out of memory (Fixed with UR7 for DPM 2016 and already part of DPM 2019 RTM):One of the top scenario where we observed the 40002 error is due to WMI out of memory. In a scenario, where you see 40002 error in DPM Console and at the same time you may see WMI-Activity error event ID 5858 logged with Result code 0�80041006. This code translates to �not enough memory for the operation�. To address this issue, with DPM 2016 UR 7 we increased the default WMI memory limit from 20MB to 60MB by adding registry keys (details below). This change is already part of DPM 2019 RTM.If you still see the same failure, the work around could be to increase this limit a bit more. But if the issues persists, there could be more reasons why the calls to WMI might fail. It could be due to inadequate OS resources causing WMI to perform slow or the degraded performance of underlying storage. Our team is investigating further on how we can isolate these issues.Registry Key Details:Reg Key : HKLM\SOFTWARE\Microsoft\Wbem\CIMOMValue: High Threshold On Events (B)Data (String) : 60000000Reg Key : HKLM\SOFTWARE\Microsoft\Wbem\CIMOMHigh Threshold On Client Objects (B)Data (String) : 60000000Sparse file issue with Windows Server 2016:If this issue is specifically seen, when DPM 2019 /2016 is installed on Windows Server 2016, please check if event ID 27268 is logged in the Hyper-V-VMSS logs with the description as �Virtual hard disk files must be uncompressed and unencrypted and must not be sparse�.To resolve this issue , install the latest updates for Windows Server 2016.If you are still experiencing high frequency of this error, please reach out to our customer support team to troubleshoot further.
