Please upload any relevant screenshots that would help illustrate the problem. I want to ensure that I fully understand the issue at hand so that I can provide the best possible solution.
We need to find out what is behind the 500 error. The first step is to enable debugging. You can add a few lines to the site’s wp-config.php file. With the error log enabled, you will see the actual problem.
To enable it, open your wp-config.php file and look for define('WP_DEBUG', false);. Change it to:
define('WP_DEBUG', true);
To enable the error logging to a file on the server, you need to add yet one more similar line:
define( 'WP_DEBUG_LOG', true );
The errors will be saved to a debug.log file inside the /wp-content/directory.
