What does Windows error code 8309 (ERROR_DS_USER_BUFFER_TO_SMALL) mean?

ERROR_DS_USER_BUFFER_TO_SMALL

The user buffer is too small.

Windows assigns decimal 8309 and hexadecimal 0x00002075 to ERROR_DS_USER_BUFFER_TO_SMALL. The decisive subject is a caller-provided buffer for directory-service output; the value alone does not reveal which object, server, file, session, or transition failed.

The native Value is 8309 (0x00002075). Preserve this result immediately after the failing Windows call because later logging, cleanup, LDAP, RPC, or file operations can replace the last-error value.

Where the result appears

• processing a caller-provided buffer for directory-service output.
• 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 a caller-provided buffer for directory-service output and does not by itself prove that the entire server, directory, disk, session, or application is unavailable. The state boundary to prove for it is whether the output buffer is large enough for the complete directory result and any terminator or structure alignment. Use supplied and required byte counts, API and structure version, and encoding and element count as independent evidence. When evidence for it disagrees, preserve timestamps and investigate the transition instead of selecting the most convenient value.

Likely causes

• the caller ignored the required-size result.
• the data grew between sizing and retrieval.
• character count was mistaken for byte count.
• structure version or alignment was calculated incorrectly.

Diagnostic sequence

1. capture error 8309 immediately at the API boundary and record the operation that was attempted.
2. identify the exact owner of a caller-provided buffer for directory-service output, including object generation, server, path, session, replica, or client context.
3. collect supplied and required byte counts before restarting a service or changing configuration.
4. compare API and structure version with the documented or observed precondition.
5. correlate encoding and element count 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

• supplied and required byte counts.
• API and structure version.
• encoding and element count.
• whether the operation supports a two-call sizing pattern.

Correlate this result 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 8309; 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 allocate from the returned required size with overflow checks, repeat the retrieval, and cap untrusted sizes before allocation.

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_user_buffer_to_small_api for the producing function or management operation.
• record ds_user_buffer_to_small_target for the file, log, session, replica, object, or server identity.
• record ds_user_buffer_to_small_state_before and ds_user_buffer_to_small_requested_transition.
• record ds_user_buffer_to_small_first_status for the earliest lower-level diagnostic.

For support escalation involving it, retain decimal 8309, hexadecimal 0x00002075, 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_INSUFFICIENT_BUFFER is the general Win32 form; this directory-specific value identifies the DS operation

Practical validation scenario

A tool sizes a buffer in UTF-16 characters but passes that number as bytes. Logging both units exposes the mismatch, and allocating the required byte count resolves it. 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 8309, hexadecimal 0x00002075, 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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