What does HRESULT 0xC00E0093 (MQ_ERROR_UNSUPPORTED_CLASS) mean?

MQ_ERROR_UNSUPPORTED_CLASS

Interpretation

MQ_ERROR_UNSUPPORTED_CLASS belongs to the Message Queuing HRESULT facility, but its useful meaning is narrower than a generic messaging failure. In this case the decisive subject is AD DS object class is outside MSMQ supported set. The directory object may be valid LDAP data but not a class that MSMQ APIs know how to process.

For MQ_ERROR_UNSUPPORTED_CLASS, A domain join, a successful DNS lookup, and an LDAP bind are separate checkpoints. When diagnosing MQ_ERROR_UNSUPPORTED_CLASS, directory errors must be correlated with the exact naming context, object class, GUID, and domain controller used by MSMQ.

When diagnosing MQ_ERROR_UNSUPPORTED_CLASS, MSMQ uses directory services for public queues, machine configuration, security metadata, routing, aliases, and related enterprise objects. In the MQ_ERROR_UNSUPPORTED_CLASS path, private/direct queue operation can therefore succeed while a directory-dependent action fails.

Relevant API contract

When diagnosing MQ_ERROR_UNSUPPORTED_CLASS, A queue can exist locally while its public registration or MSMQ configuration object is absent, stale, wrong-class, or visible only on some domain controllers. For MQ_ERROR_UNSUPPORTED_CLASS, the code-specific boundary is AD DS object class is outside MSMQ supported set.

Decisive observations

• The directory object class, guid, owner, and replication state; associate it explicitly with MQ_ERROR_UNSUPPORTED_CLASS.
• When diagnosing MQ_ERROR_UNSUPPORTED_CLASS, domain/workgroup mode, forest and domain names, and selected domain controller; capture the value before cleanup or retry changes it.
• In the MQ_ERROR_UNSUPPORTED_CLASS path, dns and ldap reachability plus the distinguished name being accessed; compare it with a known-good call using the same account and queue type.
• For this MQ_ERROR_UNSUPPORTED_CLASS result, record the queue path or format name, local/remote placement, transactional flag, caller SID, process build, and UTC correlation ID when they apply.

For MQ_ERROR_UNSUPPORTED_CLASS, log certificate thumbprints, provider names, SIDs, GUIDs, lengths, and hashes where useful, but do not log private keys, symmetric keys, credentials, or confidential message bodies.

Troubleshooting workflow

1. Record the unsigned HRESULT, MQ_ERROR_UNSUPPORTED_CLASS, and the native API or COM method before a framework replaces it with a generic exception.
2. Reproduce with the smallest queue/message/property set that still returns MQ_ERROR_UNSUPPORTED_CLASS; change one precondition at a time.
3. In the MQ_ERROR_UNSUPPORTED_CLASS path, verify the postcondition after the failed call: queue existence, message presence, directory object state, transaction outcome, or generated output may differ by result.
4. For this MQ_ERROR_UNSUPPORTED_CLASS result, capture domain/workgroup mode, forest and domain names, and selected domain controller.
5. For MQ_ERROR_UNSUPPORTED_CLASS, capture DNS and LDAP reachability plus the distinguished name being accessed.
6. When diagnosing MQ_ERROR_UNSUPPORTED_CLASS, apply the code-specific recovery rule: Use the documented MSMQ schema object or a generic LDAP tool for unrelated classes.

Recovery rules

Use the documented MSMQ schema object or a generic LDAP tool for unrelated classes.

When diagnosing MQ_ERROR_UNSUPPORTED_CLASS, do not hide this HRESULT behind an unlimited framework retry. In the MQ_ERROR_UNSUPPORTED_CLASS path, require a verified precondition change and preserve the original correlation identifier across the next attempt.

Differences that matter

In the MQ_ERROR_UNSUPPORTED_CLASS path, local private-queue success does not prove that public-queue registration, global catalog discovery, or the required AD DS object is healthy. The specific focus for MQ_ERROR_UNSUPPORTED_CLASS remains AD DS object class is outside MSMQ supported set.

• In the MQ_ERROR_UNSUPPORTED_CLASS path, changing queue names, deleting directory objects, or recreating certificates without reconciliation can create a second object while callers still reference the first.
• For this MQ_ERROR_UNSUPPORTED_CLASS result, A successful test under an interactive administrator account does not prove that the production service account has the same profile, token, directory access, or key permissions.

Practical scenario

A domain-mode queue installer encounters MQ_ERROR_UNSUPPORTED_CLASS. For MQ_ERROR_UNSUPPORTED_CLASS, it compares DNS, LDAP bind, object class, and replication on the exact domain controller used by MSMQ. When diagnosing MQ_ERROR_UNSUPPORTED_CLASS, the acceptance test then changes only the decisive precondition and confirms both the HRESULT and the actual queue/message state.

A regression test should force MQ_ERROR_UNSUPPORTED_CLASS, assert the raw value and relevant outputs, then correct only the documented precondition and verify the intended success or neighboring HRESULT.

Sources

• Microsoft: Message Queuing error and information codes — source used for the MQ_ERROR_UNSUPPORTED_CLASS analysis.
• Microsoft Open Specifications: MSMQ and directory services — source used for the MQ_ERROR_UNSUPPORTED_CLASS analysis.
• Microsoft Open Specifications: MSMQ protocols overview — source used for the MQ_ERROR_UNSUPPORTED_CLASS analysis.
• IETF RFC 4511: LDAP protocol — source used for the MQ_ERROR_UNSUPPORTED_CLASS analysis.
• Microsoft: destination queues — source used for the MQ_ERROR_UNSUPPORTED_CLASS analysis.

Looking for a different code? Search another status or error code.