Unable to examine files in web view after upgrade. Please help

After performing a do-release-upgrade as outlined in this post to get from 14.04 to 16.04, it appears to have MOSTLY worked, but I am now seeing this error when trying to view a file with the web interface.

ActionView::Template::Error ('nil' is not an ActiveModel-compatible object. 
It must implement :to_partial_path.):

It appears that the versions of git are the same:

gitlabs version

/opt/gitlab/embedded/bin/git --version
git version 2.7.4

system version

which git

/usr/bin/git --version
git version 2.7.4

Current Linux info:

lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.1 LTS
Release:        16.04
Codename:       xenial

Current Gitlab info:

GitLab 8.12.7
GitLab Shell 3.6.1
GitLab Workhorse 0.8.2
GitLab API v3
Git 2.7.4
Ruby 2.3.1p112
PostgreSQL 9.2.18

Also, this is for the Omnibus edition.

Please advise