I am trying to use xdebug in phpstorm. I have successfully installed xdebug and set the path in php.ini. However, I am still getting message that "failed loading usr/lib/php/20151012/xdebug.so:undefined sybol:zend_sort".
My php executable is "php-cgi-5.6.20"
My php.ini: zend_extension = "/usr/lib/php/20151012/xdebug.so"
With the same zend_extension path try to use php executable '7.0', and not '5.6'. It worked for me.