What does HRESULT 0x8001012E (CO_E_CONVERSIONFAILED) mean?

 
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CO_E_INVALIDSID CO_E_NOMATCHINGSIDFOUND

CO_E_CONVERSIONFAILED

Trustee string conversion failed

CO_E_CONVERSIONFAILED is HRESULT 2147549486 (0x8001012E) from winerror.h. AllStat describes it as “Unable to convert a wide character trustee string to a multibyte trustee string.” 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 hexadecimal value and symbolic name this result should remain attached to the originating API and operation generation.

Decisive interpretation boundary

Before choosing recovery, verify that source encoding, code page, destination capacity, invalid-character policy, and account-name round trip are explicit. If this condition cannot be proven for it, stop before consuming outputs or repeating side effects.

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.

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 conversion of a wide trustee name to a multibyte representation required by a legacy access-control path. Keep it attached to that operation; the same numeric severity outside the owning API does not supply enough context.

Correct handling and recovery

Keep Unicode end to end where possible; otherwise use strict conversion with required-size calculation and reject lossy identity transformations.

Backoff alone is not a repair for it; a measurable state or configuration transition must justify another attempt.

Difference from nearby HRESULTs

It is character conversion; trustee syntax and lookup HRESULTs describe later identity parsing or resolution.

A support tool discussing it should name the neighboring result only after the originating API and decisive state are known.

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.

Developer and administrator guidance

When it crosses native, managed, scripting, RPC, or WinRT projection boundaries, preserve the unsigned 32-bit HRESULT. Unit tests for it should assert the code-specific postcondition and resource ownership, not merely that an exception was thrown.

After it, avoid broad permission grants or system-wide resets unless code-specific evidence proves a global configuration problem. Define who owns retry, cancellation, cleanup, policy changes, package repair, and user-facing messaging for it.

Practical scenario

A trustee contains characters absent from the configured ANSI code page. The component switches its persistence format to Unicode instead of substituting question marks.

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.

References

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