I’ve just finished rolling out a new WordPress site which uses the very nice Divi theme by Elegant Themes.  The site is hosted on Pair, and they do not have gzip compression enabled for Apache.  No problem I thought, someone must have solved that problem.  And sure enough Jon Henshaw had done exactly that.  There’s something not quite right with the way his blog is rendering (because it’s removed the underscores from the code) but basically all I had to do was put this at the top of my child theme header.php file:

ob_start("ob_gzhandler");

Once I’d done that I verified (using Google Chrome) that the download size of the each page on the site had decreased, and sure enough the 500K home page was now just a 100k download. Woot. Or so I thought.

Next morning I got up to a slew of emails asking me what happened to the site as all people could see was a blank page. I checked the site in Chrome, nope, it’s there. Checked it in Firefox, nope it’s there. Checked in IE10, nope there too. All there while I was logged into WordPress. With a growing sense of dread I logged out of WordPress in IE10, refreshed the home page of the site and….a blank page. Same for FireFox and for some reason, Chrome rendered the site just fine. I tracked the problem down to somewhere in the wp_head() call in the header.php file, but I really wasn’t interested in having the site down any longer so I removed the offending code above and the site started working correctly.

Today, with a bit of time on my hands I tested the same call in a couple of other themes (WP 2014 and on this blog) and it didn’t cause an issue. So, the only thing I can conclude at this stage is that ob_gzhandler and the Divi WordPress theme do not play well together.