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TBS_E_BUFFER_TOO_LARGE
Classify the layer correctly
TBS_E_BUFFER_TOO_LARGE (0x8028400E) belongs to the public and internal TPM Base Services path. The base What Is page already shows the short Windows message; the additional diagnostic value is that this result marks a public TBS input or requested output size exceeds the service’s accepted maximum.
The first producer to identify for TBS_E_BUFFER_TOO_LARGE is the TBS client library, local RPC service and command scheduler before or around device execution. For TBS_E_BUFFER_TOO_LARGE, tBS centralizes TPM access through a local RPC service. For TBS_E_BUFFER_TOO_LARGE, a failure can therefore occur in the caller contract, RPC/service startup, scheduling, buffer handling or TPM submission, and each layer requires different evidence.
Incident worksheet
Preserve these TBS_E_BUFFER_TOO_LARGE items before changing anything:
TBS_E_BUFFER_TOO_LARGEand0x8028400E, the exact returning method or command, and the first nested status.- cbCommand, output capacity, arithmetic used to build lengths, structure nesting, command header paramSize, and TBS_IN_OUT_BUF_SIZE_MAX.
- The TPM generation, manufacturer/firmware revision, Windows build, caller identity and TBS/provider state for
TBS_E_BUFFER_TOO_LARGE. - The complete opaque
TBS_E_BUFFER_TOO_LARGErequest artifacts, redacting authorization secrets but not rewriting structure boundaries.
A reproducible comparison
Run this focused check: submit a minimal valid command and then test the exact documented boundary size. Do not combine the TBS_E_BUFFER_TOO_LARGE test with firmware updates, TPM clearing, account changes, key recreation and policy edits in the same trial; such a result cannot isolate this boundary.
| Checkpoint | Pass condition |
|---|---|
| a public TBS input or requested output size exceeds the service’s accepted maximum | The original TBS_E_BUFFER_TOO_LARGE command reaches the next defined state without returning this result. |
| Security behavior | The TBS_E_BUFFER_TOO_LARGE verification still uses the intended TPM, authorization, locality and policy. |
| Output integrity | The object, digest, event log or state transition produced after TBS_E_BUFFER_TOO_LARGE validates independently. |
Boundaries often confused with this one
| Related result | Separate meaning |
|---|---|
TBS_E_ACCESS_DENIED | The caller does not have the appropriate rights to perform the requested operation — a separate checkpoint when compared with TBS_E_BUFFER_TOO_LARGE. |
TBS_E_COMMAND_CANCELED | The command was canceled — a separate checkpoint when compared with TBS_E_BUFFER_TOO_LARGE. |
TBSIMP_E_BUFFER_TOO_SMALL | The specified buffer was too small — a separate checkpoint when compared with TBS_E_BUFFER_TOO_LARGE. |
The practical distinction is that TBS_E_INSUFFICIENT_BUFFER means a legitimate result does not fit in a smaller caller buffer.
Restore service safely
The supported direction is to validate lengths before allocation and split only at protocol-defined boundaries; do not truncate a TPM command. For TBS_E_BUFFER_TOO_LARGE, do not restart or disable TBS before capturing its service and event data. For TBS_E_BUFFER_TOO_LARGE, most caller-contract errors are reproducible without touching TPM ownership, firmware state or stored keys.
If the same bytes still return TBS_E_BUFFER_TOO_LARGE after the documented preconditions are satisfied, retain this code-specific trace for the platform vendor or Windows component owner rather than erasing state.
Technical references
- Microsoft: About TPM Base Services — source for the
TBS_E_BUFFER_TOO_LARGEcheckpoint. - Microsoft: TBS return codes — source for the
TBS_E_BUFFER_TOO_LARGEcheckpoint. - Microsoft: Tbsi_Context_Create — source for the
TBS_E_BUFFER_TOO_LARGEcheckpoint. - Microsoft: Tbsip_Submit_Command — source for the
TBS_E_BUFFER_TOO_LARGEcheckpoint.
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