What does HRESULT 0xC800040E (hrBufferTooSmall) mean?

 
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hrFileAccessDenied hrTooManyColumns

hrBufferTooSmall

Why this is more specific than the message text

hrBufferTooSmall means a caller-provided output area cannot hold the value ESE is returning.

This is the legacy Directory Service backup/restore HRESULT form of JET_errBufferTooSmall (0xC800040E).

The key comparison is: hrInvalidBufferSize usually means a fixed-size column contract mismatch, not a grow-and-retry output pattern. The first useful observation is to record supplied capacity, returned required length, encoding, structure version, and whether partial data is documented. This evidence separates malformed input from a valid name, path, or buffer that simply produced no result.

Related ESE conditions

hrInvalidPatha database, system, log, or temporary directory does not satisfy the path contract
hrInvalidBufferSizethe supplied byte count is incompatible with the selected column type or operation
hrInvalidParameterthe function received a value or combination that violates its call contract

The ESE objects in play

Diagnostic layerAPI argument, naming, path, and buffer contracts
Typical API surfacethe specific Jet* function named by the caller and its structure definitions in esent.h
Code-specific conditiona caller-provided output area cannot hold the value ESE is returning
First corrective directionallocate from the required length, retain overflow checks, and repeat only a non-destructive read where possible

Many output APIs expose a required byte count, while fixed-width inputs must match a declared type exactly. The original Unicode value and byte length matter when diagnosing names and paths.

Data for a reproducible case

  • Code-specific observation: record supplied capacity, returned required length, encoding, structure version, and whether partial data is documented.
  • the documented required-size value for any output buffer; associate it with this result rather than with a later generic exception.
  • the unmodified argument value with its Unicode and byte lengths.
  • structure sizes, reserved fields, grbits, and API version.

Corrective workflow

  1. Freeze the failing request context and record 0xC800040E, the Jet API name, and the current instance/session ownership.
  2. Verify the code-specific precondition: record supplied capacity, returned required length, encoding, structure version, and whether partial data is documented.
  3. Apply the targeted fix: allocate from the required length, retain overflow checks, and repeat only a non-destructive read where possible.
  4. Before retrying the operation, reconcile the exact argument bytes and the absence of unintended object creation.

Actions that can hide or worsen the problem

  • Do not silently trim, recode, or sanitize the value into a different identifier.
  • Do not grow a fixed-width input buffer as though it were a variable output.

Technical references


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