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CO_E_FAILEDTOQUERYCLIENTBLANKET
COM could not query the client security blanket
CO_E_FAILEDTOQUERYCLIENTBLANKET is HRESULT 2147549480 (0x80010128) from winerror.h. AllStat describes it as “Unable to obtain the client's security blanket.” In the COM IAccessControl, DCOM client identity, trustee translation, token inspection, security descriptor, ACL, or serialization workflow, the code identifies a specific failure boundary and should not be replaced by a generic COM exception.
The caller should keep this result intact through logging, exception translation, and RPC or language projection boundaries.
Where it is encountered
- IAccessControl initialization, access checks, owner/trustee processing, and serialized ACL persistence. Record the interface, method, component version, thread, apartment, process, and correlation ID.
- Server-side DCOM impersonation, client blanket inspection, token and SID lookup.
- Security descriptor construction, DACL canonicalization, file-backed policy storage, or legacy NetAccess migration.
The immediate focus for it is server authorization or auditing that calls <code>CoQueryClientBlanket</code> but cannot retrieve authentication service, principal, level, capabilities, or identity. Keep it attached to that operation; the same numeric severity outside the owning API does not supply enough context.
Decisive interpretation boundary
Before choosing recovery, verify that the call context is active and secured, and blanket querying occurs before asynchronous handoff or method return. The decisive boundary for it determines whether the same object can continue, a new object is required, or policy must change.
Also confirm that all observed objects, tokens, buffers, proxies, metadata files, or ACLs belong to the current operation generation and were not retained from an earlier attempt.
Difference from nearby HRESULTs
It concerns binding metadata; CO_E_FAILEDTOGETSECCTX is broader failure to obtain the server security context.
A support tool discussing it should name the neighboring result only after the originating API and decisive state are known.
Correct handling and recovery
Inspect the binding and call timing, keep the query inside the server method, and reject identity-sensitive work when blanket details are unavailable.
Backoff alone is not a repair for it; a measurable state or configuration transition must justify another attempt.
Practical scenario
A server queues authorization to a worker then queries the client blanket there. It captures the approved blanket fields during the original call.
A regression test should reproduce it, assert the raw HRESULT and all relevant outputs, then correct only the decisive condition and verify the intended success or neighboring failure result.
Lifetime, retry, and cleanup rules
After it, determine whether the current object, interface pointer, call context, token, stream, metadata reader, asynchronous operation, or access-control instance remains valid. Release only resources owned by the failing attempt, cancel callbacks through their documented mechanism, and avoid double close, double commit, repeated activation, or replay of a non-idempotent remote method.
The retry policy for it should state the trigger, maximum attempts, cancellation owner, and reconciliation step for effects that may have completed elsewhere.
References
- Microsoft: IAccessControl
- Microsoft: IAccessControl::IsAccessAllowed
- Microsoft: AccessCheck
- Microsoft: LookupAccountSidW
- Microsoft: LookupAccountNameW
- Microsoft: access control lists
- Microsoft: canonical ACE order
- Microsoft: HRESULT values
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