Knowledge

DNS_ERROR_UNSUPPORTED_ALGORITHM - 9105 (0x2391)

The specified algorithm is not supported.

Updated: Feb 21, 2026

Technical Background

The DNS_ERROR_UNSUPPORTED_ALGORITHM error code is a specific error encountered in the Windows Domain Name System (DNS) client API. This error indicates that an operation was attempted using an algorithm that is not supported by the current configuration or implementation.

Error Details

  • Error Name: DNS_ERROR_UNSUPPORTED_ALGORITHM
  • Numeric Code: 9105
  • Hex Code: 0x2391
  • Short Description: The specified algorithm is not supported.

This error typically arises when a request or operation is made that requires an algorithm which is either disabled, unsupported by the current version of Windows, or not enabled in the DNS client configuration.

Common Causes

The DNS_ERROR_UNSUPPORTED_ALGORITHM error can be caused by several factors:

  • Unsupported Algorithm: The requested cryptographic algorithm is not supported by the system or the current version of the DNS client software.
  • Configuration Issues: The DNS client settings may be configured to use an unsupported algorithm, leading to this error.

Real-World Context

This error can occur in various scenarios where cryptographic algorithms are used for secure communication or data integrity checks. For instance, it might appear when attempting to configure a DNS server with an algorithm that is not supported by the client's version of Windows.

Is This Error Critical?

The criticality of this error depends on the specific context and the importance of the operation being performed. If the operation involves secure communication or data integrity checks, then this error could be significant as it may indicate a security vulnerability or configuration issue that needs to be addressed.

How to Diagnose

To diagnose the DNS_ERROR_UNSUPPORTED_ALGORITHM error, follow these steps:

  1. Review Operation Context: Ensure that the operation being performed is appropriate for the current system and version of Windows.
  2. Validate Parameters: Check if the parameters passed to the DNS client API include a supported algorithm. Verify that the algorithm name or identifier matches those supported by the system.
  3. Confirm Object Types: Confirm that the object types involved in the operation are correctly identified and supported by the current configuration.
  4. Verify Input Data: Ensure that all input data, including cryptographic keys or parameters, are valid and compatible with the system's capabilities.
  5. Check Limits or Constraints: Verify that there are no operational limits or constraints that could prevent the use of certain algorithms.

How to Resolve

To resolve the DNS_ERROR_UNSUPPORTED_ALGORITHM error, consider these practical steps:

  • Correct Parameter Usage: Ensure that all parameters passed to the DNS client API include supported algorithms. Refer to the documentation for a list of supported algorithms.
  • Adjust Operation Context: If the operation context is incorrect or outdated, adjust it to ensure compatibility with the current system version and configuration.
  • Restore Data: If corrupted data is suspected, restore from a known good backup or reconfigure the DNS client settings.
  • Retry Operation with Valid Inputs: Attempt the operation again using valid inputs that are compatible with the supported algorithms.

Developer Notes

Developers should ensure that their applications and configurations are up to date and compatible with the latest versions of Windows and the DNS client API. Regularly check for updates and patches that may address compatibility issues or introduce new algorithms.

Related Errors

  • DNS_ERROR_ALGORITHM_MISMATCH: Occurs when an algorithm mismatch is detected during secure communication.
  • DNS_ERROR_UNSUPPORTED_SECURITY_PROTOCOL: Indicates that a security protocol not supported by the system was requested.

FAQ

Q: What does the DNS_ERROR_UNSUPPORTED_ALGORITHM error mean?

A: The specified cryptographic algorithm is not supported by the current configuration or implementation of the DNS client API.

Q: How can I prevent this error from occurring?

A: Ensure that your system and applications are up to date, and verify that all parameters passed to the DNS client API include supported algorithms.

Q: Can this error be critical for security?

A: Yes, if the operation involves secure communication or data integrity checks, then this error could indicate a security vulnerability that needs immediate attention.

Summary

The DNS_ERROR_UNSUPPORTED_ALGORITHM error code indicates that an unsupported cryptographic algorithm was requested. This can occur due to configuration issues or limitations in the current system version. By following diagnostic and resolution steps, developers can address these errors effectively and ensure secure and reliable operation of their applications.