Hello,
Now, the client in the delivery zone above cannot finish the checkout process (error 500 when clicks on finish)
In that case, can you :
- Activate the Joomla debug mode ("Administration->Global configuration->System->Debug System/Language")
- Set the "error reporting" option of the Joomla configuration to "maximum"
- Test it again so that you can see if it display an error message which will help you to understand from what your issue is coming.
Note that you can also look in the PHP error log of your web server for the error message corresponding to the problem, it will tell you the source of the problem.
Kind regards,
Mohamed Thelji.