What does HRESULT 0x803100D9 (FVE_E_OSV_KSR_NOT_ALLOWED) mean?

FVE_E_OSV_KSR_NOT_ALLOWED

Read this as a state-machine result

FVE_E_OSV_KSR_NOT_ALLOWED is a BitLocker facility HRESULT, not a Win32 filesystem error wrapped by an application. In this case policy forbids the requested Key Storage Root operation while the operating-system volume remains protected.

BitLocker evaluates the target volume together with effective Group Policy or MDM policy, Windows edition, caller authorization and the requested protector or management method. A policy HRESULT therefore describes a rejected configuration decision, not evidence that encrypted sectors are damaged.

What the code does not prove

The closest misleading interpretation is a generic unsupported capability; the operation is recognized but incompatible with protected OS-volume policy. 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

A managed restriction is part of the security design. Record which authority delivered it and whether the requested operation is mandatory for compliance or merely a convenience feature.

A low-risk recovery path

• Use the documented policy-approved key-management workflow and avoid disabling protection solely to bypass the restriction.

manage-bde -status
gpresult /h bitlocker-policy.html

State checks specific to FVE_E_OSV_KSR_NOT_ALLOWED

References

• Microsoft: Configure BitLocker policy
• Microsoft: BitLocker CSP reference
• Microsoft: BitLocker operations guide
• Microsoft: COM error codes for FVE