PHP Process page 404'ing when sending back a good JSON response - php

Question

Have a sendmail.php page that i'm calling via ajax on a WordPress site.
This is the basics of how it looks:
if ($_POST) {
foreach($_POST as $field => $val) {
if ($val == '') {
$jsonReturn = ['success' => false, 'message' => 'Validation errors whilst processing your form, please go back and check.'];
echo json_encode($jsonReturn);
die();
}
}
if ($noErrors) { // set elsewhere, but works okay
/*
Send an email
*/
if ($mail->send()){
$jsonReturn = ['success' => true, 'message' => "Thank you, message sent."];
echo json_encode($jsonReturn);
}
}
} else {
header("Location: /");
die();
}
If the 'validation' fails at the top of the page, I get a 200 page back containing the JSON return of success false.
However, if I pass validation and send the email thens end the json return it 404's the page.
I tested also by putting:
$jsonReturn = ['success' => true, 'message' => "Thank you, message sent."];
echo json_encode($jsonReturn);
Directly under the first foreach and it also 404's. So im guessing there is something wrong with that?
Any help.

Answer 1

Sorted, the input field has a name of "name".
Changing that worked, speaking to a colleague it appears that WordPress has a certain set of field names reserved for its queries. In this case it was seeing the field name and sending the request off to another page which doesn't exist.
Im sure a person with more knowledge at WP can explain better, but for now if anyone comes across this issue just make sure to check the input names.