What does HRESULT 0x80042406 (VSS_E_ASRERROR_DATADISK_RDISK0) mean?

VSS_E_ASRERROR_DATADISK_RDISK0

The firmware-active disk is a data disk. ASR has found that the disk treated as the primary firmware recovery disk is actually a data disk. The legacy description recommends selecting another active disk or cleaning the data disk before retrying, but either action is destructive or boot-critical and must be validated first.

The documented condition is: “A data disk is currently set as active in BIOS. Set some other disk as active or use the DiskPart utility to clean the data disk, and then retry the restore operation.”

Where VSS_E_ASRERROR_DATADISK_RDISK0 appears

The failure appears during system-disk identification in bare-metal recovery, when ASR must decide which target will receive the bootable system layout.

Likely causes

• An MBR partition on a data disk is marked active even though the disk is not intended to host the restored system.
• Firmware disk ordering or virtual-machine attachment order makes an auxiliary disk appear first.
• A reused target retains old boot flags or partition metadata.
• External or removable storage changes the disk enumeration seen by Windows RE.

Evidence to capture before changing storage

• Capture firmware boot mode and boot order before changing any disk.
• Use DiskPart to list disks, partitions and active flags, recording serial numbers and sizes.
• Identify every existing filesystem and confirm which disks contain data that must be preserved.
• Record how ASR selected the recovery disk rather than assuming disk 0 is always the correct system target.

Diagnostic sequence

• Determine whether the machine boots in BIOS/MBR or UEFI/GPT mode; the active flag has different relevance.
• Detach unnecessary external disks temporarily when doing so is operationally safe.
• Compare the intended target identity with firmware and hypervisor ordering.
• Treat clean as irreversible; never use it merely to test whether the HRESULT disappears.

Recovery and retry

Correct boot selection or prepare a verified empty target according to the recovery plan. If cleaning is required, first prove that the disk has no data that must survive and that the backup includes everything needed. Then restart ASR so it rediscovers the disk layout.

What this HRESULT does not prove

This code does not mean the data disk is defective or too small. The conflict is its role in boot/recovery selection.

Difference from nearby VSS results

VSS_E_ASRERROR_RDISK0_TOOSMALL accepts the firmware-active disk role but rejects its capacity. Here the role itself is wrong because the selected disk is a data disk.

Practical example

A VM has an old data VHD attached before the new recovery target. The data VHD contains an active MBR partition, so ASR selects it as the primary recovery disk and stops before overwriting it.

Guidance for backup software and telemetry

User interfaces should display disk identity, current content and the exact proposed boot role before offering corrective actions. A one-click cleanup recommendation is unsafe here.

Official Microsoft references

• Microsoft: VSS Automated System Recovery for disaster recovery
• Microsoft: DiskPart active command
• Microsoft: DiskPart inactive command
• Microsoft: DiskPart command interpreter