update to D8.5.1 via Composer and website unavailable

Please consider me a newbie, but I’ve been working through installation of composer and drush to permit an update to Drupal 8.5.1 today. I worked through all the normal operations and followed tips and tricks found in tutorials and support tickets all over this wonderful forum. Presently, I’m FREAKING OUT because while the composer update appeared to work just fine, when I go to the website I only get:

The website encountered an unexpected error. Please try again later. (internal server error 500)

Reading through posts, I’ve pulled the server logs and they can be viewed here: https://www.dropbox.com/s/k5ka7lbmwegyne3/error_log.txt?dl=0

I’m still able to see most of the administrative parts of Drupal, but when I click on ‘Configuration’ within the Drupal admin panel, I get the same internal server error (500).

Any assistance that can be provided is greatly appreciated, and I presume there’s more information that is needed, so please advise.


Drupal version: 

Source: https://www.drupal.org/taxonomy/term/21/feed