The solution was found here: Jira integration page is not opening in Gitlab. Integration has stopped working
Specifically, after running the upgrade, and executing gitalb-ctl reconfigure, run through the following steps:
sudo gitlab-rake db:migrate:status
and make sure all migrations are up. If they are, run the following two commands:
sudo gitlab-rake db:migrate:redo VERSION=20200123155929
sudo gitlab-rake db:migrate:redo VERSION=20200127090233