> ## Documentation Index
> Fetch the complete documentation index at: https://auth0.com/llms.txt
> Use this file to discover all available pages before exploring further.

> Customizing error messages with Lock

# Customize Lock Error Messages

export const AuthCodeBlock = ({filename, icon, language, highlight, children}) => {
  const [displayText, setDisplayText] = useState(children);
  const [copyText, setCopyText] = useState(children);
  const wrapperRef = React.useRef(null);
  useEffect(() => {
    let unsubscribe = null;
    function init() {
      if (!window.autorun || !window.rootStore) {
        return;
      }
      unsubscribe = window.autorun(() => {
        let processedChildrenForDisplay = children;
        let processedChildrenForCopy = children;
        for (const [key, value] of window.rootStore.variableStore.values.entries()) {
          const escapedKey = key.replaceAll(/[.*+?^${}()|[\]\\]/g, (String.raw)`\$&`);
          let displayValue = value;
          if (key === "{yourClientSecret}" && value !== "{yourClientSecret}") {
            displayValue = value.substring(0, 3) + "*****MASKED*****";
          }
          processedChildrenForDisplay = processedChildrenForDisplay.replaceAll(new RegExp(escapedKey, "g"), displayValue);
          processedChildrenForCopy = processedChildrenForCopy.replaceAll(new RegExp(escapedKey, "g"), value);
        }
        setDisplayText(processedChildrenForDisplay);
        setCopyText(processedChildrenForCopy);
      });
    }
    if (window.rootStore) {
      init();
    } else {
      window.addEventListener("adu:storeReady", init);
    }
    return () => {
      window.removeEventListener("adu:storeReady", init);
      unsubscribe?.();
    };
  }, [children]);
  useEffect(() => {
    if (!wrapperRef.current) return;
    const originalWriteText = navigator.clipboard.writeText.bind(navigator.clipboard);
    let isOverriding = false;
    const handleClick = e => {
      const button = e.target.closest('[data-testid="copy-code-button"]');
      if (!button || !wrapperRef.current.contains(button)) return;
      isOverriding = true;
      navigator.clipboard.writeText = text => {
        if (isOverriding) {
          isOverriding = false;
          navigator.clipboard.writeText = originalWriteText;
          return originalWriteText(copyText);
        }
        return originalWriteText(text);
      };
      setTimeout(() => {
        if (isOverriding) {
          isOverriding = false;
          navigator.clipboard.writeText = originalWriteText;
        }
      }, 100);
    };
    const wrapper = wrapperRef.current;
    wrapper.addEventListener('click', handleClick, true);
    return () => {
      wrapper.removeEventListener('click', handleClick, true);
      if (navigator.clipboard.writeText !== originalWriteText) {
        navigator.clipboard.writeText = originalWriteText;
      }
    };
  }, [copyText]);
  return <div ref={wrapperRef}>
      <CodeBlock filename={filename} icon={icon} language={language} lines highlight={highlight}>
        {displayText}
      </CodeBlock>
    </div>;
};

<Warning>
  At this time, Auth0’s active development efforts are focused on Universal Login, and Classic Login no longer receives updates. To customize your login pages, Auth0 recommends [Advanced Customizations for Universal Login](/docs/customize/login-pages/advanced-customizations).
</Warning>

You can customize the error messages that will be displayed in certain situations by providing a `languageDictionary` option. A full listing of available `languageDictionary` fields to customize can be found in the GitHub repository's [English Dictionary file for Lock](https://github.com/auth0/lock/blob/master/src/i18n/en.js). Below is an example of some customized error messages:

export const codeExample = `// Examples of customized error messages in the languageDictionary option
var options = {
  languageDictionary: {
    error: {
      login: {
        "lock.invalid_email_password": "Custom message about invalid credentials",
        "lock.network": "Custom message indicating a network error and suggesting the user check connection",
        "lock.unauthorized": "Custom message about a failure of permissions",
        "too_many_attempts": "Custom message indicating the user has failed to login too many times."
      },
      signUp: {
        "invalid_password": "Custom message indicating a password was invalid",
        "user_exists": "Custom message indicating that a user already exists"
      }
    }
  }
};

// Initiating our Auth0Lock
var lock = new Auth0Lock(
  '{yourClientId}',
  '{yourDomain}',
  options
);`;

<AuthCodeBlock children={codeExample} language="javascript" />

## Custom errors in Rules

If you are returning custom error codes from a [rule](/docs/customize/rules) or a custom database script, you can handle custom errors:

* In your application's redirect URL by reading the `error` and `error_mesage` query string parameters.
* By redirecting the user back to your hosted pages with a custom error message and displaying the message with a [flash message](/docs/libraries/lock/lock-api-reference).

## Learn more

* [Lock for Web](/docs/libraries/lock)