Why does it throw NetworkError: Failed to execute 'send'...?

Question

JavaScript

Previously, there was filtering of articles, everything worked, from incomprehensible times an error began to appear in this code:

POST https://xn----7sbbkgwzu0b5a9d0b.xn--p1ai/abhazija/index.php?option=com_ajax&module=filter_materials&method=getFiltermaterials&format=json 
send @ jquery.min.js:4
ajax @ jquery.min.js:4
call @ gagra.html:717
onsubmit @ gagra.html:455
Object {readyState: 0, status: 0, statusText: "NetworkError: Failed to execute 'send' on 'XMLHttp…materials&method=getFiltermaterials&format=json'."}

Code that used to work:

jQuery.ajax({
        type:'POST',
        url:'index.php?option=com_ajax&module=filter_materials&method=getFiltermaterials&format=json',
        async: true,
         data: {'tag1' : tag1,'tag2' : tag2,'tag3' : tag3,'tag4' : tag4}, 
        success:function (data) {//возвращаемый результат от сервера
        	console.log(data);
          jQuery.each(JSON.parse(data), function(index, item) {
            materialsOK.push(item);
          })  
        },
        error:function(data){
            console.log(data);
        }
    	});

What could be the problem?