What does Windows error code 4440 (ERROR_OFFLOAD_READ_FLT_NOT_SUPPORTED) mean?

 
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ERROR_SECUREBOOT_NOT_SUPPLEMENTAL_POLICY ERROR_OFFLOAD_WRITE_FLT_NOT_SUPPORTED

ERROR_OFFLOAD_READ_FLT_NOT_SUPPORTED

A filter in the source path cannot process offloaded reads

ODX begins by asking the source stack for a token that represents a file range. File-system minifilters that transform, inspect, or virtualize data must explicitly participate so that the token represents the same bytes an ordinary read would return. This error identifies a filter limitation, not necessarily a storage-array limitation.

Enumerate minifilters on the source volume and identify which one vetoes or does not implement offload-read handling. Encryption, antivirus, hierarchical storage, deduplication, or other data-transforming filters may legitimately force a normal buffered copy. Verify behavior with the filter disabled only in a controlled test; production software should fall back to ReadFile and WriteFile semantics when ODX is unavailable.

What to inspect

  • List minifilters attached to the source volume.
  • Determine whether any filter transforms source file data.
  • Confirm the copy path falls back safely to ordinary I/O.

References


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