I have updated my rails api application from 5.1 to 5.2. I am using rails api only. I am trying to use the active storage. I think the problem is due to the line conf
conf
Having this in the config
require "active_storage/engine"
and running this
bundle exec rails active_storage:install
This worked for me. I updated from rails 5.1 to 6.0.2.1