No post found Ultimate wp query search

No post found on other langauge, my site has two languages and on one works perfectly, and on another one no post found. I am using ajax results with predefined dropdown lists.

I am using wp 4.8 and wpml 3.7.1. NO errors in console.

Search is normally worked until a few days ago.

Do you know what problem is? In my error log i see this warning on both languages:

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function ‘search_filter’ not found or invalid function name in wp-includes/class-wp-hook.php on line 298