Knowledge

WSA_QOS_EFILTERSTYLE - 11019 (0x2B0B)

An invalid QOS filter style was used.

Updated: Feb 21, 2026

Technical Background

The WSA_QOS_EFILTERSTYLE error is a specific error code returned by the Windows Socket (Winsock) API when an invalid Quality of Service (QoS) filter style is used. This error indicates that the application attempted to set or use a QoS filter with an unsupported or incorrect style.

Error Details

The WSA_QOS_EFILTERSTYLE error code, 11019 in decimal and 0x2B0B in hexadecimal, signifies that the Quality of Service (QoS) filter being used is not valid. This can occur when an application tries to configure a QoS policy with a style that is not supported by the system or the specific network interface.

Common Causes

  • Invalid Parameter Values: The application may have passed an unsupported QoS filter style as a parameter to a Winsock function, such as SetQOS or GetQOS.
  • Incorrect Object Type: The operation might be applied to an object that does not support QoS filtering, such as a socket type that is not capable of setting QoS policies.

Real-World Context

This error typically occurs in network programming scenarios where applications attempt to configure Quality of Service settings for network traffic. Applications using the Winsock API need to ensure they are passing valid QoS filter styles and applying them correctly to supported objects.

Is This Error Critical?

The criticality of this error depends on the application's requirements. If the application relies heavily on QoS features, such as prioritizing certain types of network traffic, then encountering this error can be significant. However, if the application does not use QoS extensively or has fallback mechanisms in place, the impact might be minimal.

How to Diagnose

  1. Review Operation Context: Ensure that the operation is being performed on a socket type that supports QoS filtering. For example, some socket types may not support setting QoS policies.
  2. Validate Parameters: Check the parameters passed to functions like SetQOS or GetQOS. Verify that the QoS filter style is one of the supported styles by the system and the specific network interface.
  3. Confirm Object Types: Confirm that the object being operated on (e.g., a socket) supports the QoS filtering operation. Some socket types may not support setting QoS policies, so ensure compatibility.
  4. Verify Input Data: Ensure that all input data related to QoS settings is valid and correctly formatted according to the API specifications.

How to Resolve

  1. Correct Parameter Usage: Use a supported QoS filter style when configuring network traffic. Refer to the documentation for the specific Winsock functions to determine which QoS filter styles are supported.
  2. Adjust Operation Context: If the operation is being performed on an object that does not support QoS filtering, consider using a different socket type or adjusting the application logic to avoid this error.
  3. Restore Data: If invalid data was passed as parameters, correct it and retry the operation.
  4. Retry Operation with Valid Inputs: Ensure all inputs are valid before attempting the operation again.

Developer Notes

Developers should consult the official Winsock documentation for a list of supported QoS filter styles and ensure that their applications handle these errors gracefully to maintain robust network programming practices.

Related Errors

  • WSAEINVAL (10022): Invalid argument. This error might be encountered if an invalid parameter is passed, but it does not specifically indicate the use of an unsupported QoS filter style.
  • WSAENOSUPPORT (998): Operation not supported on socket. This error can occur if the operation being attempted is not supported by the specific socket type or network interface.

FAQ

What causes WSA_QOS_EFILTERSTYLE?

This error occurs when an invalid QoS filter style is used, such as passing a non-supported value to functions like SetQOS or GetQOS.

How can I prevent this error?

Ensure that you are using supported QoS filter styles and validating all parameters before calling Winsock functions. Consult the documentation for specific API requirements.

Can this error be ignored?

If the application does not rely heavily on QoS features, it might be acceptable to ignore this error. However, in scenarios where QoS is critical, addressing this error is recommended.

Summary

The WSA_QOS_EFILTERSTYLE error indicates that an invalid Quality of Service filter style was used. Developers should ensure they are using supported styles and validating all parameters when working with the Winsock API to avoid this error.