Can't administer cividiscount afer upgrade to 4.7.7
I was having the same issue (Joomla 3.5/CiviCRM 4.7.8) after a tests on my local install, I found that activating the debug (Administer > System Settings > Debugging &amp; Error Handling), browsing the CiviDiscount loaded. Turned off debug and loaded. Hope this may help.