What does HRESULT 0x803100A5 (FVE_E_FULL_ENCRYPTION_NOT_ALLOWED_ON_TP_STORAGE) mean?

FVE_E_FULL_ENCRYPTION_NOT_ALLOWED_ON_TP_STORAGE

Read this as a state-machine result

FVE_E_FULL_ENCRYPTION_NOT_ALLOWED_ON_TP_STORAGE is a BitLocker facility HRESULT, not a Win32 filesystem error wrapped by an application. In this case full-volume encryption was requested on thin-provisioned storage, where BitLocker permits only Used Space Only conversion.

Cluster Shared Volumes and thin-provisioned storage add ownership and allocation semantics that a standalone disk does not have. BitLocker operations must respect the CSV coordinator and must not force thin backing storage to allocate every virtual extent.

What the code does not prove

The closest misleading interpretation is a small or nearly full volume; the restriction prevents allocation expansion of thin backing storage. Verify the returning method and state transition before assigning the incident to disk corruption, TPM failure or bad credentials.

Inspect the target, not just the message

Cluster maintenance should preserve resource ownership, quorum assumptions and application shutdown ordering. BitLocker is only one participant in that workflow.

A low-risk recovery path

• Use Used Space Only encryption and monitor backing allocation; do not force a full sweep that defeats thin provisioning.

Get-ClusterSharedVolume | Format-List *
manage-bde -status

State checks specific to FVE_E_FULL_ENCRYPTION_NOT_ALLOWED_ON_TP_STORAGE

References

• Microsoft: GetConversionStatus method
• Microsoft: COM error codes for FVE
• Microsoft: Protect cluster shared volumes and SANs
• Microsoft: BitLocker operations guide