ajax error 400 4,jquery - ajax error 400 bad request - Stack Overflow

I am trying to upload file using ajax in yii2.

but it browser console it shows 400 Bad Request in my site_url

what is my mistake..

Please help anyone.

var site_url = '<?php echo Url::to (['formdata/movefile','id'=>'']); ?>' + unic ;

var file_data = $('#formdata-'+ form + '-' + component + '-c_data').prop('files')[0];

var form_data = new FormData();

form_data.append('file', file_data);

$.ajax({

url: site_url, // point to server-side PHP script

dataType: 'TEXT', // what to expect back from the PHP script, if anything

cache: false,

contentType: false,

processData: false,

data: { form_data:form_data,_csrf : '=Yii::$app->request->getCsrfToken()?>'},

type: 'POST',

success: function(php_script_response){

alert(php_script_response);

}

});