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TPM_E_FAMILYCOUNT
The state machine behind the code
TPM_E_FAMILYCOUNT means a delegation blob or family operation carries a verification count that no longer matches the current TPM 1.2 family state.
Evidence table
| Question | Evidence |
|---|---|
| What exact state was rejected? | a delegation blob or family operation carries a verification count that no longer matches the current TPM 1.2 family state |
| Which layer owns the result? | The TPM 1.2 NV permission and lifecycle checks. |
| What must be correlated? | family ID, family count in the TPM, count embedded in the blob, family create or invalidate history, and ownership changes |
| Controlled comparison | retrieve current family state and build a fresh delegation blob tied to that count |
Separate caller data from platform state. The caller data includes the command, structures, lengths, handles and flags; platform state includes TPM generation, provisioning, locality, lockout, resource inventory, firmware and the TBS service lifecycle. This result is actionable only after the rejected side is identified.
Reproduction plan
Use the following verification sequence:
- Capture the unmodified failing input and
0x80280040. - Retrieve current family state and build a fresh delegation blob tied to that count.
- Compare the first divergent field or state transition.
- Repeat the operation only after restoring the same baseline, with a bounded retry policy where the specification permits retry.
Contrast with neighboring results
| Other code | Why a different remedy follows |
|---|---|
TPM_E_WRITE_LOCKED | The NV area has already been written to. |
TPM_E_PER_NOWRITE | There is no protection on the write to the NV area. |
TPM_E_BAD_ATTRIBUTES | The NV area attributes conflict. |
TPM_E_INVALID_FAMILY means the family identifier itself is not valid. The difference determines whether to change serialization, authorization, resource lifetime, firmware/PPI state, command policy or only retry timing.
Confirming remediation
Correct the original boundary by choosing this direction: replace stale delegated credentials after any family-state change instead of editing the count field. Do not undefine a production NV index until its public attributes and authorization policy have been recorded. NV policy is established at definition time, and destructive recreation can remove counters, certificates or provisioning state.
Technical references
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