What does Windows error code 8571 (ERROR_DS_NAME_NOT_UNIQUE) mean?

ERROR_DS_NAME_NOT_UNIQUE

The requested name already exists as a unique identifier.

ERROR_DS_NAME_NOT_UNIQUE belongs to Active Directory Domain Services (AD DS). A diagnosis of this result must connect the condition to the producing API, current state, object identity, and first lower-level diagnostic.

This result is Win32 error 8571 (0x0000217B) in Active Directory Domain Services (AD DS). Interpret it at the call that produced it and use the system message above as the immediate condition rather than as a complete root cause.

Where the result appears

• processing an Active Directory name expected to be a unique identifier.
• executing an LDAP, RPC, deployment, replication, or directory-management operation.
• working against a specific domain controller whose replica and schema state affect the result.
• translating extended directory diagnostics into a Win32 error for an application or administration tool.

State boundary to prove

This result applies to an Active Directory name expected to be a unique identifier and does not by itself prove that the entire server, directory, disk, session, or application is unavailable. The state boundary to prove for this Win32 error is whether the requested name maps to exactly one object in the relevant namespace and naming context. Use requested name and attribute, all matching object DNs and GUIDs, and search base and scope as independent evidence. When evidence for this Win32 error disagrees, preserve timestamps and investigate the transition instead of selecting the most convenient value.

Likely causes

• duplicate names exist where uniqueness is required.
• replication conflict created ambiguous entries.
• the caller searches too broad a namespace.
• a stale object retains the name.

Diagnostic sequence

1. capture error 8571 immediately at the API boundary and record the operation that was attempted.
2. identify the exact owner of an Active Directory name expected to be a unique identifier, including object generation, server, path, session, replica, or client context.
3. collect requested name and attribute before restarting a service or changing configuration.
4. compare all matching object DNs and GUIDs with the documented or observed precondition.
5. correlate search base and scope with the Directory Service event log, LDAP extended diagnostics, replication metadata, dcdiag and repadmin output, and the calling application’s request trace.
6. determine whether side effects occurred and verify recovery after changing one responsible condition.

Evidence to collect

• requested name and attribute.
• all matching object DNs and GUIDs.
• search base and scope.
• replication conflict metadata.

Correlate it with the Directory Service event log, LDAP extended diagnostics, replication metadata, dcdiag and repadmin output, and the calling application’s request trace. Keep the first detailed status even when a later wrapper translates it to error 8571; the first status often distinguishes transport, authorization, storage, schema, state, and application-integrity causes that share the same final Win32 result.

Handling, retry, and recovery

The recovery objective is to remove or rename the conflicting object through supported tools, narrow the namespace where appropriate, and retry using a stable object identity.

Retry it only after the recorded condition changes and completion state is known. Idempotent queries may be repeated after recovery, but mutations require a state check first; backoff cannot repair malformed input, corruption, missing structure, or policy rejection.

Telemetry and support fields

• record ds_name_not_unique_api for the producing function or management operation.
• record ds_name_not_unique_target for the file, log, session, replica, object, or server identity.
• record ds_name_not_unique_state_before and ds_name_not_unique_requested_transition.
• record ds_name_not_unique_first_status for the earliest lower-level diagnostic.

For support escalation involving it, retain decimal 8571, hexadecimal 0x0000217B, the API, UTC time, target identity, and first subsystem-specific status. Include the smallest reproducible request and evidence that distinguishes this condition from nearby codes. In the context of it, many ds codes are internal or management-facing and are not tied to one public function. the producing ldap, rpc, deployment, or management api must therefore be recorded with the code.

Difference from nearby results

ERROR_DS_DUPLICATE_ID_FOUND concerns a non-unique identifier on retrieval; this code specifically reports that the requested name is not unique

Practical validation scenario

A provisioning tool searches the forest for a supposedly unique service name and finds objects in two domains. Using the intended domain scope and cleaning the stale object restores uniqueness. The negative test should preserve the responsible condition and reproduce it; the recovery test should change only the identified cause, repeat the same operation, and verify both success and the absence of an unintended partial side effect.

Developer and administrator guidance

Administrators handling it should preserve Directory Service events, replication metadata, and the contacted domain controller before changing objects or forcing role transitions. Developers should retain LDAP extended diagnostics and object identities across wrappers so the Win32 code does not erase the actionable directory result. Code that exposes it through RPC, JSON, REST, PowerShell, or another protocol should preserve the Win32 domain, decimal 8571, hexadecimal 0x0000217B, and original component diagnostic.

References

• Microsoft: Win32 system error range containing this code — official context relevant to it.
• Microsoft: AD DS troubleshooting — official context relevant to it.
• Microsoft: repadmin — official context relevant to it.
• Microsoft: dcdiag — official context relevant to it.
• Microsoft: AD and LDS diagnostic event logging — official context relevant to it.

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