What does HRESULT 0x00040ED7 (DB_S_NOTSINGLETON) mean?

DB_S_NOTSINGLETON

OLE DB returned the first row from a non-singleton result

DB_S_NOTSINGLETON is HRESULT 265943 (0x00040ED7) from Microsoft OLE DB. AllStat describes DB_S_NOTSINGLETON as “Row object was requested on a non-singleton result; First row was returned.” The high-order severity bit is clear, so this is a success result, but it carries more information than plain S_OK.

A row object was requested where the result contained more than one row, so the provider returned the first row with a warning.

Evidence and telemetry to preserve

• For DB_S_NOTSINGLETON, preserve query and key parameters.
• For DB_S_NOTSINGLETON, preserve actual match count.
• For DB_S_NOTSINGLETON, preserve ordering clause.
• For DB_S_NOTSINGLETON, preserve returned row identity.
• For DB_S_NOTSINGLETON, preserve unique constraints and isolation level.

Also record db_s_notsingleton_operation, db_s_notsingleton_object, db_s_notsingleton_state_before, db_s_notsingleton_state_after, UTC time, process and thread identifiers, and a correlation ID. For DB_S_NOTSINGLETON, keep secrets out of logs while retaining GUIDs, CLSIDs, media subtypes, property IDs, row identities, and hashes needed to distinguish objects.

Where this result is encountered

• DB_S_NOTSINGLETON can appear in commands requesting a single row object; record the producing interface and method rather than inferring behavior from the symbolic name alone.
• DB_S_NOTSINGLETON can appear in lookup queries expected to be unique; record the producing interface and method rather than inferring behavior from the symbolic name alone.
• DB_S_NOTSINGLETON can appear in providers converting rowsets into row objects; record the producing interface and method rather than inferring behavior from the symbolic name alone.

For DB_S_NOTSINGLETON, the same numeric success value can be mishandled when a wrapper exposes only a Boolean. For DB_S_NOTSINGLETON, keep the original HRESULT until the code-specific outputs and state transition have been evaluated.

State boundary that must be proved

The central question for DB_S_NOTSINGLETON is whether the caller verifies uniqueness instead of accepting the arbitrary first row as the only match. For DB_S_NOTSINGLETON, the HRESULT alone confirms neither unrelated work nor the quality of optional outputs.

A reliable interpretation of DB_S_NOTSINGLETON names the exact method contract, the object generation, and the outputs that remain valid. For DB_S_NOTSINGLETON, this prevents a success-with-information result from being promoted to full success or demoted to a generic error.

Diagnostic sequence

• For DB_S_NOTSINGLETON, capture the raw HRESULT 0x00040ED7 immediately after the returning method and record whether the caller used SUCCEEDED, FAILED, equality testing, or exception translation.
• Identify the exact owner of DB_S_NOTSINGLETON: interface, method, object instance, provider or filter version, thread or apartment, and operation phase.
• Validate the decisive contract boundary for DB_S_NOTSINGLETON: the caller verifies uniqueness instead of accepting the arbitrary first row as the only match.
• For DB_S_NOTSINGLETON, inspect every output parameter, count, status array, returned interface, or side effect that the method documentation associates with this success-with-information result.
• Compare the observed state before and after DB_S_NOTSINGLETON; do not assume that a success severity bit means every optional sub-operation completed.
• For DB_S_NOTSINGLETON, reproduce the smallest request with the same object state and then change only the condition identified by the evidence before repeating the operation.

Difference from nearby HRESULT values

S_OK for a singleton confirms the request matched the contract; DB_S_NOTSINGLETON reports multiple rows hidden behind a first-row result.

For DB_S_NOTSINGLETON, this distinction determines whether the caller should consume partial outputs, stop iteration, wait, reconfigure, notify the user, or perform no error recovery at all.

Correct handling, retry, and recovery

Treat the row as provisional, report or resolve the uniqueness violation, and change the query or schema so the intended record is deterministic.

Retry DB_S_NOTSINGLETON only when the recorded state can change the documented outcome. For DB_S_NOTSINGLETON, repeating the same call is inappropriate for a stable end marker, cancellation, unsupported format, adjusted property, or partial result whose completed side effects have not been reconciled.

Practical validation scenario

A user lookup expected one account but duplicate email records exist. The provider returns the first with DB_S_NOTSINGLETON; the application refuses authentication and starts data cleanup.

The negative test should preserve the condition that produces DB_S_NOTSINGLETON; the recovery test should alter only that condition and verify the final state as well as the HRESULT.

Developer and administrator guidance

For DB_S_NOTSINGLETON, application telemetry should separate terminal failure, ordinary success, partial completion, continuation, cancellation, and warning-like success. For DB_S_NOTSINGLETON, support bundles should contain the smallest reproducible call and the effective configuration seen by the owning component.

A support report for DB_S_NOTSINGLETON should include decimal 265943, hexadecimal 0x00040ED7, the AllStat meaning, the owning API, and the first detailed status or output that explains why the method did not return ordinary S_OK.

References

• Microsoft: OLE DB return codes — official documentation relevant to DB_S_NOTSINGLETON.
• Microsoft: OLE DB Driver return codes — official documentation relevant to DB_S_NOTSINGLETON.
• Microsoft: OLE DB error records — official documentation relevant to DB_S_NOTSINGLETON.

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