1) If you get the following error when deploying Solid Cache.
ArgumentError: You can only specify one of :database, :databases, or :connects_to (ArgumentError)
2) The reason is likely you added connects_to in your configuration file. It conflicts with the database config created by default.
# config/cache.yml
production:
database: cache
<<: *default
# config/environments/production.rb
config.solid_cache.connects_to = { database: { writing: :cache } }
3) To fix the error, keep only one of the above.
4) It is slightly confusing at the moment. Solid Queue creates connects_to as default, but Solid Cache creates database as default.