Why is the server refusing to accept when sending data with a POST request (Axios)?

Question

AJAX

Hello.
There is such js-library Axios.
When you send data in a POST request to the server (PHP) like this:
" axios.post('site.com', 'session=1&text=blabla' )", then PHP accepts it in $_POST.
But when you post, in a different way: axios.post('site.com', { sessions:1, text: blabla }) . That answer is related to CORS, an error.
The question is why the server accepts the first option, and refuses the second option?
and how to fix it?

Answer 1

Of course, you didn't point out the error.
I assume that the problem is related to preflight requests. The server must correctly respond to OPTIONS requests with a 200 response code and all CORS headers.