To provide helpful feedback to users when errors occur in a GUI:

1. Be clear and concise: Use simple language to explain the error.

2. Be specific: Clearly state what went wrong and why.

3. Provide context: Explain how to fix the error or what to do next.

4. Use visual cues: Highlight error fields or use icons to draw attention.

5. Use non-technical language: Avoid technical jargon or codes.

6. Offer solutions: Provide suggestions or alternatives to fix the error.

7. Be timely: Display feedback immediately after the error occurs.

8. Be consistent: Use consistent language and formatting for error messages.

9. Provide recovery options: Allow users to easily recover from errors.

10. Test with users: Ensure feedback is helpful and effective through user testing.

Additionally, consider:

- Using a friendly and approachable tone

- Providing additional resources or help links

- Offering real-time validation to prevent errors

- Using animation or micro-interactions to draw attention

- Ensuring accessibility for all users

By providing helpful feedback, you can turn a negative experience into a positive one, helping users understand and recover from errors, and improving the overall user experience.