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DB_S_COLUMNTYPEMISMATCH
OLE DB copy detected incompatible column types
DB_S_COLUMNTYPEMISMATCH is HRESULT 265921 (0x00040EC1) from Microsoft OLE DB. AllStat describes this result as “One or more column types are incompatible; Conversion errors will occur during copying.” The high-order severity bit is clear, so this is a success result, but it carries more information than plain S_OK.
The copy or transfer operation continued, but one or more source and destination column types are incompatible and conversions can fail.
Where the result is encountered
- This result can appear in rowset copy operations; record the producing interface and method rather than inferring behavior from the symbolic name alone.
- This result can appear in schema migration through OLE DB; record the producing interface and method rather than inferring behavior from the symbolic name alone.
- It can appear in bulk transfer between providers with different type systems; record the producing interface and method rather than inferring behavior from the symbolic name alone.
The same numeric success value can be mishandled when a wrapper exposes only a Boolean. Keep the original HRESULT until the code-specific outputs and state transition have been evaluated.
Diagnostic sequence
- capture the raw HRESULT
0x00040EC1immediately after the returning method and record whether the caller usedSUCCEEDED,FAILED, equality testing, or exception translation. - Identify the exact owner of it: interface, method, object instance, provider or filter version, thread or apartment, and operation phase.
- Validate the decisive contract boundary for it: each column mapping is inspected and conversion status is checked before the destination is considered complete.
- 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 it; do not assume that a success severity bit means every optional sub-operation completed.
- reproduce the smallest request with the same object state and then change only the condition identified by the evidence before repeating the operation.
State boundary that must be proved
The central question for it is whether each column mapping is inspected and conversion status is checked before the destination is considered complete. The HRESULT alone confirms neither unrelated work nor the quality of optional outputs.
A reliable interpretation of it names the exact method contract, the object generation, and the outputs that remain valid. This prevents a success-with-information result from being promoted to full success or demoted to a generic error.
Correct handling, retry, and recovery
Correct mappings or add explicit conversions. If partial copying is allowed, quarantine rows with conversion errors and reconcile counts before commit.
Retry it only when the recorded state can change the documented outcome. 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.
Evidence and telemetry to preserve
- preserve source and destination metadata.
- preserve ordinal mapping.
- preserve DBTYPE values, precision, scale, and length.
- preserve per-column status values.
- preserve rows rejected or truncated during conversion.
Also record db_s_columntypemismatch_operation, db_s_columntypemismatch_object, db_s_columntypemismatch_state_before, db_s_columntypemismatch_state_after, UTC time, process and thread identifiers, and a correlation ID. Keep secrets out of logs while retaining GUIDs, CLSIDs, media subtypes, property IDs, row identities, and hashes needed to distinguish objects.
Difference from nearby HRESULT values
DB_S_TYPEINFOOVERRIDDEN says caller-supplied parameter metadata replaced provider inference; it identifies incompatible mapped columns.
This distinction determines whether the caller should consume partial outputs, stop iteration, wait, reconfigure, notify the user, or perform no error recovery at all.
Developer and administrator guidance
Application telemetry should separate terminal failure, ordinary success, partial completion, continuation, cancellation, and warning-like success. Support bundles should contain the smallest reproducible call and the effective configuration seen by the owning component.
A support report for it should include decimal 265921, hexadecimal 0x00040EC1, the AllStat meaning, the owning API, and the first detailed status or output that explains why the method did not return ordinary S_OK.
Practical validation scenario
A migration copies a Unicode identifier into a narrow numeric destination column. The provider warns before conversion; the tool changes the schema mapping and reruns in a transaction.
The negative test should preserve the condition that produces it; the recovery test should alter only that condition and verify the final state as well as the HRESULT.
References
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