Look at your pages through 'view source' in your browser. You will see at the very top something like: $prev = ($i == 0) ? $total : $i-1; at the very top.
That shouldn't be there and may have been created by a trashed zuul/index.php or exhibition plugin (we can't see the actual php code from here, just the results)
also, you'll see other things in red, which may be related: why is it missing head tags, for example?
I can't see the htaccess file at the root, which means you're either missing it or it's been renamed to .htaccess for clean urls -- in this last case you need to change your defaults.php mod_rewrite to 'true' again
Lastly, any customization you may have done to your system files (note your site folder files) will have been lost with the update and need to be redone -- this is also in the update instructions
the issue is probably in your exhibition plugin, which shouldn't have been touched by the update. I hope you made a backup of your old installation before udating (as specified in the instructions for the update), because it would be useful to see which of all the errors had been there before the update