HRESULT 0x80284011 (TBS_E_NO_EVENT_LOG): meaning and diagnosis

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Description:

TBS could not provide a TCG measured-boot event log for the current boot.

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TBS_E_SERVICE_DISABLED	TBS_E_ACCESS_DENIED

TBS_E_NO_EVENT_LOG

PCR values need the event log for explanation

TBS_E_NO_EVENT_LOG means no TCG/WBCL event log is available through TBS. The log records measured-boot events and the digests extended into platform configuration registers. PCR values can still exist without a retrievable log, but an attestation verifier then lacks the ordered evidence needed to reconstruct and interpret those measurements.

Absence can result from firmware behavior, unsupported boot mode, collection failure, an empty log, or a read problem. It is not equivalent to a PCR mismatch and does not by itself prove that boot was compromised.

What to investigate

Use the TBS log API's size-query pattern and handle variable-size TPM 2.0 event structures.
Check whether the system booted in UEFI measured-boot mode and whether firmware supplied an event log.
Review TPM provisioning readiness information for an empty or unreadable TCG log condition.
Preserve PCR readings and boot-mode details even when the event log cannot be retrieved.

References

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