To customize error messages on Joomla, follow these steps:
1. Log in to the Joomla back-end
2. Go to System > Global Configuration
3. Click on the System tab
4. Scroll down to the Debug Settings section
5. Change the “Debug System” option to “Yes”
6. Change the “Error Reporting” option to “Maximum”
7. Click on the Server tab
8. Scroll down to the Error Pages section
9. Choose the error status code you want to customize (e.g. 404 Not Found)
10. Enter the text you want to display in the “Error message” field
11. Click on the Save & Close button
You can repeat steps 9-11 for each error status code you want to customize. Custom error messages will now be displayed when users encounter errors on your Joomla site.
