An AJAX HTTP error occurred. HTTP Result Code: 500

Error happens both on acquia dev desktop 2 rc and on ubuntu 14.04 + nginx + php5-fpm

Please see attachments

Using:

• Facetapi
• Search api solr
• Views

My default theme: Omega Kickstart 7.x-3.4

Error log message:

2015/03/17 07:10:57 [error] 32634#0: *898 FastCGI sent in stderr: "PHP 
message: PHP Fatal error: Call to a member function execute_display() on
a non-object in
...../all/modules/ajax_facets/ajax_facets.pag$
on line 35" while reading response header from upstream, client:
5.76.222.218, server: mydomainname.com, request: "POST
/ru/ajax/ajax_facets/refresh/ HTTP/1.1", upstream:
"fastcgi://unix:/var/lib/php5-fpm/web7.sock:", host:
"mydomainname.com", referrer:
"http://mydomainname.com/en/categories"