Qualys vulnerability scanner VM and PAYLOAD_BLOCK_ZERO error

[Frosty]

Attempts to take backup of a freshly-deployed (yesterday) Qualys vulnerability scanner appliance VM on HyperV result in the following error:

Processing QUALYS-HyperV Error: VHDx:CVhdxDisk.InitialValidation: Incorrect bitmap entry type (PAYLOAD_BLOCK_ZERO): See [MS-VHDX-v1.00-20160128] specification section 3.4.1.2. Agent failed to process method {VHDX.GetDiskInformation}.
Error: VHDx:CVhdxDisk.InitialValidation: Incorrect bitmap entry type (PAYLOAD_BLOCK_ZERO): See [MS-VHDX-v1.00-20160128] specification section 3.4.1.2. Agent failed to process method {VHDX.GetDiskInformation}.
Processing finished with errors at 25/09/2025 9:50:23 AM

Doesn't matter whether or not I have the VM powered ON or OFF. It is a fairly inconsequential VM and I can probably just shut it down and take a copy using Windows Explorer ... but ... I guess I am curious ... the VM runs fine ... am wondering if Qualys deliberately engineered this to prevent backup copies being made?

[david.domask]

Hi Frosty,

Quick look at Qualys' documentation tells that there is no need to back up the appliances.

I'm afraid only Qualys will be able to answer if they engineered their appliance to not be backed up, but based on the error, it does seem like they do something a bit goofy with the VHDX, but further analysis would require a Support Case and a review of the debug logs.

All in all, I would follow the appliance vendor's guidance and not do backups of the appliance and follow the vendor's guidance for recovery.

[Frosty]

Thanks David -- in the meantime I have done a HyperV Export of the VM, set that aside "just in case" -- I'll take your advice and just go with documenting the network config of the appliance and leave it at that.