Are you experiencing a blank frontend/frontpage after upgrading to Joomla 3.5?
Chances are that you have either of these two problems;
1) Non compatible Template.
If you like me are using Artisteer as your template development software, simply open your current template in a current version of Artisteer, then save and export a new template. Then install the new template onto your Joomla site and activate this. Finally clear the cache to see if that has made any difference to you.
If you however are using a purchased template, then look to see if there has been an update released by the template developer.
2) Non compatible Joomla Extension.
If the template trick didn't work it is likely that one of your Joomla Extensions are causing this error.
In my case it was the extension called ARI Image Slider (mod_ariimageslider) that caused this. I then simply downloaded the updated module from the developers site, installed that, and viola everything was back to normal.