I'm working with an HTML file that sends data using AJAX through POST to https://www.example.com/register_email.
If I copy & paste https://www.example.com/register_email in my browser it returns
{"status":"error","message":"Please enter Email"}
but in FileZilla I'm not able to find anything called "register_email", same goes with my hosting's file manager.
Is the site being requested by AJAX owned by you? If not, since you have no control over the site you won't see anything called "register_email" in your server's directory.
When you past it in the browser you get an error is because
Lastly if the domain (to which the request is being sent) is yours, and you still don't see anything called "registered_email" try searching using filezilla or see if there is an htaccess rule for masking the url