qTranslate X Problem with PHP 7.1 , When PHP 7.1 is enabled and you get this message on your site:

Warning: Parameter 2 to qtranxf_postsFilter() expected to be a reference, value given in /var/www/DOMAIN/htdocs/wordpress/wp-includes/class-wp-hook.php on line 298

Here how to solve qTranslate X Problem with PHP 7.1

You will find it in qtranslate-x/qtranslate_frontend.php

In line 523 change

function qtranxf_postsFilter($posts,&$query) {//WP_Query

to

function qtranxf_postsFilter($posts,$query) {//WP_Query

and in line 597 change

function qtranxf_excludeUntranslatedPosts($where,&$query) {//WP_Query

to

function qtranxf_excludeUntranslatedPosts($where,$query) {//WP_Query

Source : https://wordpress.org/support/topic/problem-with-php-7-1-2/#post-8908632