jquery & ajax getting knowledge from php in wordpress . admin-ajax.php returns 400

I’m engaged on an arbor.js graph. What I would like is to ship member id question it from php return member tree son to once more to jquery script. then print the tree.
right here is HTML kind

 <kind motion="" technique="post" id="blm_get_tree_view_meta_ajax_form" >          

        <?php echo $dropdown_html; ?>
        <enter sort="hidden" title="action" worth="blm_member_tree_response">
        <enter sort="hidden" title="blm_mem_tree_meta_nonce" worth="<?php echo $blm_add_meta_nonce ?>" />
        <enter id="<?php echo $this->plugin_name; ?>-treeview_mem_id"  sort="hidden" title="<?php echo "blm"; ?>[memid]" worth="">
        <p class="submit"><enter sort="button" title="get_tree" id="get_tree" class="button button-primary" worth="GET TREE"></p>
</kind>

And that is the jquery script

    <script>

jQuery( doc ).prepared( perform( $ ) {

"use strict";

$('#get_tree').on('click on',perform(){
    var user_id = $('#binary-level-marketting-treeview_mem_id').val();

    //console.log(user_id);
    $.ajax({
        sort:'POST',
        url: params.ajaxurl,
        knowledge:{motion:'blm_member_tree_response', user_id:user_id},
        success:perform(knowledge){
            if(knowledge.standing == 'okay') {
                console.log(knowledge.nodes);
                (perform ($) {
                var Renderer = perform (canvas) {
                            var canvas = $(canvas).get(0);
                            var ctx = canvas.getContext("2d");
                            var particleSystem;
                            var that = {
                                // arbor.js rendering goes right here.
                                
                                //....
                                //...
                            }         
                                // and renderer
                                $(doc).prepared(perform () {
                        
                                    var knowledge = {
                                        nodes: knowledge.nodes,
                                        edges: knowledge.edges
                                    }
                                    var sys = arbor.ParticleSystem(700, 700, 0.5);
                                    sys.parameters({ gravity:true});
                                    sys.renderer = Renderer("#viewport");
                                    sys.graft(knowledge);
                        
                                });
                });

})(this.jQuery);

php response perform as

 public perform getTreeGraphView() {
    
    if (isset($_POST['blm_mem_tree_meta_nonce']) && wp_verify_nonce($_POST['blm_mem_tree_meta_nonce'], 'blm_get_tree_view_meta_form_nonce'))
    {

            if(!empty($_POST['user_id'])){
    
                $knowledge = array();
                
                $mtree = new MemberTree();
                $mtree->getMemberTree($_POST['user_id']);
                $nodes_ = $mtree->getNode();
                $edges_ = $mtree->getEdge();
                $parent_ = $mtree->getParent();
                
                $knowledge['nodes'] = $nodes_;
                $knowledge['edges'] = $edges_;
            
                echo $knowledge;
                die( '0' );
            
            }
            wp_die();
        
    } else {
        wp_die(__('Invalid nonce specified', $this->plugin_name) , __('Error', $this->plugin_name) , array(
            'response' => 403,
            'back_link' => 'admin.php?web page=' . $this->plugin_name.'-product',

        ));
    }
}

ajax motion

 $this->loader->add_action( 'admin_ajax_blm_member_tree_response', $plugin_admin, 'getTreeGraphView');

enqueue scripting and localization did as it’s.

The method is 99% success however admin-aax.php returns 400 standing code. with following response

and likewise 0 append to output. I pit wpdie() at finish of the perform

I cant clear up the problem anymore. any skilled right here?