Upgrading to 4.7.7 gives Error "The website encountered an unexpected error. Please try again later."
This looks like step 11 failed.  What happens when you visit:
* Point your web browser to the following URL (you should already be logged in to Drupal with administrator-level permissions):

*- If "clean URLs" are enabled
http://&lt;your_drupal_home&gt;/civicrm/upgrade?reset=1

*- If "clean URLs" are NOT enabled
http://&lt;your_drupal_home&gt;/?q=civicrm/upgrade&amp;reset=1


Do you see errors after this?

(Sorry, I mixed posts in my head and missed the Drupal piece.  First version was for WordPress.)