Wordpress admin-ajax.php 400 bad request

Question

I have a strange and frustrating behaviour of wordpress admin-ajax.php file, when i make an ajax request it returns 400 error bad request.

(function( $ ) {
    var ajaxscript = { ajax_url : 'mydomain.com/wp-admin/admin-ajax.php' }
    $.ajax({
        url : ajaxscript.ajax_url,
        data : {
            action : 'cart_clb',
            id : 1
        },
        method : 'POST',
        success : function( response ){ console.log(response) },
        error : function(error){ console.log(error) }
    })
})(jQuery)

And inside my functions.php

add_action( 'wp_ajax_post_cart_clb', 'cart_clb' );
add_action( 'wp_ajax_nopriv_post_cart_clb', 'cart_clb' );

function cart_clb(){
    echo json_encode($_POST);
    die();
}

As said above when i execute the request :

mydomain.com/wp-admin/admin-ajax.php 400 (Bad Request)
{readyState: 4, getResponseHeader: ƒ, getAllResponseHeaders: ƒ, setRequestHeader: ƒ, overrideMimeType: ƒ, …}

Someone could help me to please? thank you.

score 35 · Answer 1 · answered Dec 29 '17 at 17:45

35

First, use full and absolute url, with protocol (or at least protocol-independent form):

var ajaxscript = { ajax_url : '//mydomain.com/wp-admin/admin-ajax.php' }

Second, your ajax action name is not the php callback function name but the dynamic part of the hook wp_ajax_{action_name} / wp_ajax_nopriv_{action_name}, so in your case it should be:

data : {
    action : 'post_cart_clb',
    id : 1
},

answered Dec 29 '17 at 17:45

Ihor Vorotnov

1,678
1
13
22

2

I think this should mark as correct answer as it highlighted issue and fix. – Rashod Chamikara Bandara Dec 28 '21 at 09:13

score 13 · Answer 2 · answered Jun 24 '21 at 17:55

13

wp_ajax_nopriv_(action) executes for users that are not logged in. So, if you want it to fire on the front-end for both visitors and logged-in users, you can do this:

add_action( 'wp_ajax_my_action', 'my_action' ); // for loggin users

add_action( 'wp_ajax_nopriv_my_action', 'my_action' ); // for non loggin users

answered Jun 24 '21 at 17:55

Rajan Vijayan

131
1
3

Ahhhhhhhh! Thank you Rajan, this was very helpful for me! – And Finally Mar 22 '22 at 10:11

score 12 · Answer 3 · edited Jan 15 '18 at 05:10

12

I have modified your code and look at this :

(function( $ ) {
var ajaxscript = { ajax_url : 'mydomain.com/wp-admin/admin-ajax.php' }
$.ajax({
    url : ajaxscript.ajax_url,
    data : {
        action : 'post_cart_clb',
        id : 1
    },
    method : 'POST', //Post method
    success : function( response ){ console.log(response) },
    error : function(error){ console.log(error) }
  })
})(jQuery)

This is the syntax of WordPress ajax : wp_ajax_{Your_action_name} wp_ajax_nopriv_{Your_action_name}

edited Jan 15 '18 at 05:10

kalpesh satasiya

799
8
18

answered Dec 29 '17 at 18:03

Lathiya Fenil

290
2
8

2

Hello, thanks for your all response, the issue is this : wp_ajax_post_cart_clb the "_post_" is not valid, i had to write wp_ajax_cart_clb where the cart_clb is the action used from ajax query. – Dec 29 '17 at 18:58
great, great. thanks for your help. I was stuck here for two hours – Ariful Islam Aug 26 '20 at 09:36

Max Lumnar · Answer 4 · 2022-05-22T18:03:11.103

7

admin-ajax.php returns Bad Request headers in 2 situations, when the action function is not registered, and when the action parameter is empty.

I had same error and the issue was that i forgot to add_action('wp_ajax_nopriv'...) i had only wp_ajax_nopriv set, so when i was logged in as admin nesting, it was not working.

edited May 22 '22 at 18:03

answered May 22 '22 at 17:56

Max Lumnar

81
1
5

score 4 · Answer 5 · answered Nov 18 '20 at 07:54

In my case, I am using Class based approach. And I found the issue was because I was using wp_ajax_ request in constructor.

If you are using ajax methods inside class, move wp_ajax_ handles outside of class (write in main plugin file) and pass classname and method name. For example:

add_action( 'wp_ajax_your_handle', [ 'Class_Name', 'function_name' ] );
add_action( 'wp_ajax_nopriv_your_handle', [ 'Class_Name', 'function_name' ] );

score 3 · Answer 6 · answered Jul 01 '21 at 15:35

3

Just Use

add_action( 'wp_ajax_my_action', 'my_action' );
add_action( 'wp_ajax_nopriv_my_action', 'my_action' );

For more detail, check the below link
https://codex.wordpress.org/AJAX_in_Plugins

answered Jul 01 '21 at 15:35

Sandeep Sherpur

2,418
25
27

score 1 · Answer 7 · answered Mar 04 '20 at 21:10

1

In Vanilla JavaScript You get a Bad Request if You don't append this header to the POST request:

request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded;');

So please be sure that jQuery appends as well that header.

answered Mar 04 '20 at 21:10

Claudio Ferraro

4,551
6
43
78

score 1 · Answer 8 · edited Mar 03 '21 at 23:44

in the url use /wp-admin/admin-ajax.php and try to have a local domain because with localhost or localhost/wordpress this might be weird, on the server this will work fine

try to use fetch or XMLHttpRequest to have more control over the request and don't send data as json send it in a formData object const formData = new FormData();

 fetch(loader.ajax_url, {
     method: "POST",
     body: formData,
 }).then((resp) => {
         console.log(resp);
 }).catch((resp) => {
         console.log(resp);
 });

it is possible to have it work with other combinations but i find this almost perfect

Wordpress admin-ajax.php 400 bad request

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