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STATUS_OFFLOAD_READ_FILE_NOT_SUPPORTED
The source file cannot participate in copy offload
This status attributes the rejection to the file rather than to a filter. ODX operates on aligned file ranges and relies on the file system and storage stack to create a stable token for the requested data. Particular file attributes, stream types, mappings, transformations, or unsupported file-system states can make that representation unavailable.
The result does not mean the file is unreadable. It means only that the optimized token path cannot be used for this file. The normal response for a copy engine is to preserve the requested range and continue through a conventional data path, while retaining the status for performance diagnostics.
What to inspect
- Record source file system, stream name, attributes, reparse tag, compression or encryption, VDL, EOF, offset, and length.
- Check logical-sector alignment and whether the requested range extends beyond valid data.
- Compare behavior with a simple uncompressed file on the same volume to isolate file-specific state.
- Verify that fallback copies the requested bytes rather than silently skipping the range.
References
- Microsoft Open Specifications: NTSTATUS values
- Microsoft: Windows Offloaded Data Transfers
- Microsoft Open Specifications: FSCTL_OFFLOAD_READ
- Microsoft: ODX compatibility guidance
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