ERROR_OFFLOAD_READ_FLT_NOT_SUPPORTED - 4440 (0x1158)
The copy offload read operation is not supported by a filter.
Updated: Feb 21, 2026
Technical Meaning
The error code ERROR_OFFLOAD_READ_FLT_NOT_SUPPORTED (4440, 0x1158) is returned when a filter driver does not support the copy offload read operation. This indicates that the requested operation cannot be performed due to limitations in the filter's capabilities.
Error Details
The ERROR_OFFLOAD_READ_FLT_NOT_SUPPORTED error code is specific to operations involving file system filters and copy offload functionality. Copy offload is a feature designed to improve performance by offloading read operations from the file system driver to lower-level hardware or software components, such as network adapters.
Usage Context
This error typically occurs in scenarios where an application or higher-level component requests a copy offload read operation through a filter driver. If the filter does not support this operation, it returns ERROR_OFFLOAD_READ_FLT_NOT_SUPPORTED to indicate that the request cannot be fulfilled.
Developer Interpretation
Developers should interpret this error as indicating that the requested operation is not supported by the current filter configuration or implementation. This could mean that either the filter driver itself does not support copy offload read operations, or the specific context in which the operation was attempted is not compatible with such a request.
Related Errors
These errors may also be encountered when attempting to perform unsupported operations through filter drivers.
FAQ
Q: What does the error code 4440 mean?
A: The error code 4440, or ERROR_OFFLOAD_READ_FLT_NOT_SUPPORTED, indicates that a copy offload read operation is not supported by a filter driver.
Q: How can I resolve this issue?
A: Ensure that the filter driver supports copy offload read operations and that the context in which the operation was attempted is compatible with such requests. If necessary, consult the documentation for the specific filter driver to understand its capabilities and limitations.
Summary
The ERROR_OFFLOAD_READ_FLT_NOT_SUPPORTED error code (4440) signifies that a copy offload read operation is not supported by a filter driver. Developers should interpret this as an indication of unsupported functionality within the current filter configuration or context.