Strict Standards: Only variables should be passed by reference on themes and som

I have no problem until i handed my site to bluhost india support team and i dont know what they did and from that time i am getting this error on top of my header
Strict Standards: Only variables should be passed by reference in customizer.php on line 111
and with most of the genesis child themes and also with few plugins. They are telling me that it was coding problem for that theme and i asked them how i am getting the same error for some plugins? They have no reply at all and just blaming that theme have coding issues. So can any one suggest me how to get rid of this problem? All my live previews look horrible and only few themes are looking as it is. For some themes i am getting avatar on top of header and while some other themes i am getting completely different look. So because of this problem i am using free theme even though i have premium themes with me. Also i am getting the same kind of error when i install new plugins and the hosting service of bluehost india is horrible. So i want to know how to do this so that i can try to get rid of this problem. I can upload the screenshots of live themes if you want.
Thanks.