To migrate OpenProject to another server (both servers on Ubuntu 16.04), I followed the instructions for OpenProject installed by DEB/RPM packages at https://www.openproject.org/operations/backup/migrating-packaged-installation-environment/. 

The new installation authenticates and runs okay, it lists my projects, but is not showing work packages. When I request Work packages, it shows the following error:

Your view is erroneous and could not be processed.

• An internal error has occurred.

I notice the production log has the following warning that is related to work package view. Could this be a clue?

W, [2018-09-26T14:14:24.990164 #1471]  WARN -- : WARNING on line 29 of /tmp/d20180926-47-3106dw/opt/openproject/app/assets/stylesheets/layout/work_packages/_full_view.sass: 
This selector doesn't have any properties and will not be rendered.

The old host server is running OpenProject 7.4.3, the new host is running OpenProject 8.0.