New answers tagged 500-internal-error
In the wp-config.php file (wordpress's root folder) you have to enable the debug. You have to set wp_debug to true. Change define('WP_DEBUG', false); to define('WP_DEBUG', true); Save the file and refresh the browser (I suggest you to use ctrl+f5). You'll see all the errors.
This likely isn't exactly an issue caused by WordPress, but due to server configurations and/or settings. 500 errors are pretty generic and can have a variety of origins, so it is hard to give the one directive that will solve it. By the way, the returning of JSON and HTML seems to be common when this happens, not sure where and it gets mixed up, might be ...
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