What does HRESULT 0x803100D4 (FVE_E_EOW_NOT_SUPPORTED_IN_VERSION) mean?

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Description:

The encrypt on write mode for BitLocker is not supported in this version of Windows. You can turn on BitLocker without using the encrypt on write mode.

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FVE_E_DE_VOLUME_NOT_SUPPORTED	FVE_E_ADBACKUP_NOT_ENABLED

FVE_E_EOW_NOT_SUPPORTED_IN_VERSION

Why this is not a generic disk error

The practical meaning of FVE_E_EOW_NOT_SUPPORTED_IN_VERSION is that Encrypt-On-Write mode was requested on a Windows version that does not implement that BitLocker conversion mode. The HRESULT is 0x803100D4.

Three decisions before remediation

Is the FVE_E_EOW_NOT_SUPPORTED_IN_VERSION target correct?: For FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, use the volume or protector GUID and confirm its role; do not rely only on a drive letter or friendly name.
Is the FVE_E_EOW_NOT_SUPPORTED_IN_VERSION request allowed?: For FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, resolve effective policy, Windows edition, caller token and management source for the volume state and geometry operation.
Is the FVE_E_EOW_NOT_SUPPORTED_IN_VERSION state stable?: For FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, record conversion, protection, lock and reboot status before modifying anything.

For FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, note: The BitLocker provider tracks encryption conversion, protection, lock state, metadata version, filesystem geometry and outstanding volume use independently. When diagnosing FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, remember: Two volumes can both appear “encrypted” in a UI while being in very different states for a management API. For FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, note: Conversion status and protection status answer different questions: sectors can be encrypted while protectors are suspended, and a fully decrypted volume can still contain stale management context in a caller.

Why a common workaround is wrong

This should not be diagnosed as ordinary Used Space Only encryption, which remains available without EOW semantics. For FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, that nearby condition needs a different corrective action and may produce a similar user-facing message.

Confirm the returning layer

For FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, record OS build, API flags, provisioning sequence, target volume and current conversion state. For FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, keep the full HRESULT and the first method that returned it because later cleanup calls can report a different state.
For FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, capture manage-bde -status and the protector inventory for the exact volume GUID, not only the drive letter, because letters can change in WinRE, clusters and deployment environments.
Export BitLocker operational events for the FVE_E_EOW_NOT_SUPPORTED_IN_VERSION failure and note the boot session, caller identity and management source; that evidence separates this BitLocker condition from a generic access or storage error.

manage-bde -status
powershell -NoProfile -Command "Get-BitLockerVolume | Format-List *"

Correct the configuration deliberately

For FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, enable BitLocker without EOW or upgrade through a supported Windows servicing path if the mode is required.
After correcting the FVE_E_EOW_NOT_SUPPORTED_IN_VERSION prerequisite, refresh protection, conversion and lock state before one controlled retry; a cached UI message is not proof that the FVE_E_EOW_NOT_SUPPORTED_IN_VERSION condition is still active.
Before a FVE_E_EOW_NOT_SUPPORTED_IN_VERSION remediation deletes protectors, changes firmware mode, resizes partitions or decrypts a production drive, verify that an independent recovery method is available and escrowed in the intended directory or account.

Treat FVE_E_EOW_NOT_SUPPORTED_IN_VERSION as a state label rather than a complete recovery plan. Confirm a successful retry with an updated BitLocker state query and a verified recovery path.

Encrypt-On-Write is a provisioning mode, not ordinary conversion

Encrypt-On-Write changes how newly written sectors are handled during early provisioning. It depends on an operating-system implementation and API flag that older Windows releases do not expose. The volume can still use conventional BitLocker encryption or Used Space Only conversion without this mode.

Remove the EOW request from the provisioning sequence or service the image to a supported release. Repartitioning the disk does not add the missing operating-system capability.

State checks specific to FVE_E_EOW_NOT_SUPPORTED_IN_VERSION

Checkpoint	How to interpret it for FVE_E_EOW_NOT_SUPPORTED_IN_VERSION
Before the call	Record the target identity and the pre-call volume state and geometry state. For FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, the decisive boundary is that Encrypt-On-Write mode was requested on a Windows version that does not implement that BitLocker conversion mode.
At failure	Preserve OS build, API flags, provisioning sequence, target volume and current conversion state. This proves whether FVE_E_EOW_NOT_SUPPORTED_IN_VERSION came from BitLocker itself or from a wrapper translating another result.
After correction	Enable BitLocker without EOW or upgrade through a supported Windows servicing path if the mode is required. The FVE_E_EOW_NOT_SUPPORTED_IN_VERSION request should then advance without removing an unrelated recovery route.
After reboot or remount	Recheck protection, conversion and lock state for FVE_E_EOW_NOT_SUPPORTED_IN_VERSION; a successful management call is incomplete if the next boot cannot unlock the volume.

Verification after the change

For FVE_E_EOW_NOT_SUPPORTED_IN_VERSION, success means more than the absence of a dialog. Confirm that the condition represented by FVE_E_EOW_NOT_SUPPORTED_IN_VERSION now matches the intended design, that the protector inventory has not lost an independent recovery route, and that the next reboot or remount can unlock the volume. If the FVE_E_EOW_NOT_SUPPORTED_IN_VERSION request advances to another HRESULT, record both values in order because that transition reveals the next unmet prerequisite.

References

Reference set for FVE_E_EOW_NOT_SUPPORTED_IN_VERSION:

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