Check for custom or unknown rules

Oct 13, 2025 by wbrum.org 65 views

Introduction

Accessibility testing is a crucial aspect of web development, ensuring that websites and web applications are accessible to people with disabilities. Axe is a popular accessibility testing tool that helps developers identify and fix accessibility issues in their web applications. However, users may encounter runtime issues while using Axe, such as the "Result for unknown rule" error. In this article, we will explore the possible causes of this error and provide solutions to resolve it.

What is Axe?

Axe is an open-source accessibility testing tool that helps developers identify and fix accessibility issues in their web applications. It provides a set of rules that check for accessibility issues, such as keyboard navigation, screen reader support, and more. Axe can be integrated into web development workflows using various tools and frameworks, including Chrome extensions, Node.js modules, and more.

Causes of the "Result for Unknown Rule" Error

The "Result for unknown rule" error occurs when Axe encounters a rule that it does not recognize or understand. This can happen when there is a mismatch between the Axe-core version and the Axe-extension version. Here are some possible causes of this error:

Mismatched Axe-core and Axe-extension versions: Axe-core and Axe-extension are two separate modules that work together to provide accessibility testing functionality. If the versions of these modules are not matched, it can lead to errors and unexpected behavior.
Outdated Axe-core version: Using an outdated version of Axe-core can lead to compatibility issues with newer Axe-extension versions, resulting in the "Result for unknown rule" error.
Unknown or custom rules: Axe provides a set of pre-defined rules for accessibility testing. However, users can also create custom rules or use third-party rules that may not be recognized by Axe.

Troubleshooting the "Result for Unknown Rule" Error

To troubleshoot the "Result for unknown rule" error, follow these steps:

Check Axe-core and Axe-extension versions: Ensure that the versions of Axe-core and Axe-extension are matched and up-to-date. You can check the versions by running the following commands in your terminal:

npm ls axe-core
npm ls axe-extension

Update Axe-core and Axe-extension: If the versions are outdated, update them to the latest versions using the following commands:

npm update axe-core
npm update axe-extension

Check for custom or unknown rules: If you have created custom rules or are using third-party rules, ensure that they are compatible with the current Axe-core version.
Disable custom rules: If you are using custom rules, try disabling them to see if the error persists.
Clear Axe cache: Clearing the Axe cache can sometimes resolve issues related to mismatched versions or unknown rules.

Example Use Case: Scanning a Small Element on the Page

When scanning a small element on the page, users may encounter the "Result for unknown rule" error. To troubleshoot this issue, follow these steps:

Check Axe-core and Axe-extension versions: Ensure that the versions of Axe-core and Axe-extension are matched and up-to-date.
Update Axe-core and Axe-extension: If the versions are outdated, update them to the latest versions.
Check for custom or unknown rules: If you have created custom rules or are using third-party rules, ensure that they are compatible with the current Axe-core version.
Disable custom rules: If you are using custom rules, try disabling them to see if the error persists.
Clear Axe cache: Clearing the Axe cache can sometimes resolve issues related to mismatched versions or unknown rules.

Conclusion

The "Result for unknown rule" error can be frustrating, especially when working with accessibility testing tools like Axe. By understanding the possible causes of this error and following the troubleshooting steps outlined in this article, developers can resolve this issue and ensure that their web applications are accessible to people with disabilities.

Best Practices for Avoiding the "Result for Unknown Rule" Error

To avoid the "Result for unknown rule" error, follow these best practices:

Keep Axe-core and Axe-extension versions matched: Ensure that the versions of Axe-core and Axe-extension are matched and up-to-date.
Use the latest Axe-core version: Using the latest Axe-core version can help resolve compatibility issues with newer Axe-extension versions.
Avoid custom or unknown rules: If you are using custom rules or third-party rules, ensure that they are compatible with the current Axe-core version.
Clear Axe cache regularly: Clearing the Axe cache can sometimes resolve issues related to mismatched versions or unknown rules.

Introduction

In our previous article, we explored the possible causes of the "Result for unknown rule" error in Axe, a popular accessibility testing tool. We also provided troubleshooting steps to resolve this issue. In this article, we will answer some frequently asked questions related to the "Result for unknown rule" error.

Q: What is the "Result for unknown rule" error in Axe?

A: The "Result for unknown rule" error occurs when Axe encounters a rule that it does not recognize or understand. This can happen when there is a mismatch between the Axe-core version and the Axe-extension version.

Q: Why do I get the "Result for unknown rule" error when scanning a small element on the page?

A: The "Result for unknown rule" error can occur when scanning a small element on the page due to a mismatch between the Axe-core version and the Axe-extension version. To resolve this issue, ensure that the versions of Axe-core and Axe-extension are matched and up-to-date.

Q: How do I check the versions of Axe-core and Axe-extension?

A: You can check the versions of Axe-core and Axe-extension by running the following commands in your terminal:

npm ls axe-core
npm ls axe-extension

Q: How do I update Axe-core and Axe-extension to the latest versions?

A: You can update Axe-core and Axe-extension to the latest versions using the following commands:

npm update axe-core
npm update axe-extension

Q: What if I have created custom rules or am using third-party rules?

A: If you have created custom rules or are using third-party rules, ensure that they are compatible with the current Axe-core version. You can try disabling custom rules to see if the error persists.

Q: How do I clear the Axe cache?

A: You can clear the Axe cache by following these steps:

Close all Axe instances: Close all Axe instances, including the Chrome extension and any other Axe-related applications.
Delete the Axe cache folder: Delete the Axe cache folder, which is usually located in the user's home directory.
Restart Axe: Restart Axe by opening the Chrome extension or running the Axe command-line tool.

Q: What are some best practices for avoiding the "Result for unknown rule" error?

A: To avoid the "Result for unknown rule" error, follow these best practices:

Keep Axe-core and Axe-extension versions matched: Ensure that the versions of Axe-core and Axe-extension are matched and up-to-date.
Use the latest Axe-core version: Using the latest Axe-core version can help resolve compatibility issues with newer Axe-extension versions.
Avoid custom or unknown rules: If you are using custom rules or third-party rules, ensure that they are compatible with the current Axe-core version.
Clear Axe cache regularly: Clearing the Axe cache can sometimes resolve issues related to mismatched versions or unknown rules.

Conclusion

Additional Resources

For more information on Axe and accessibility testing, check out the following resources:

Axe documentation: The official Axe documentation provides detailed information on how to use Axe, including troubleshooting guides and best practices.
Axe GitHub repository: The Axe GitHub repository provides access to the Axe source code, as well as information on how to contribute to the project.
Accessibility testing resources: The following resources provide additional information on accessibility testing and web accessibility:
WebAIM: WebAIM is a leading provider of accessibility testing and training resources.
W3C Web Accessibility Initiative: The W3C Web Accessibility Initiative provides information on web accessibility standards and best practices.
Deque Systems: Deque Systems is a leading provider of accessibility testing and training resources.