Can't rebuild app 'bundle exec rake db:migrate' failed

Installazione
11

hi.
When we manually execute the project into the container, we will be eating the following:
root@ubuntu-app:/var/www/discourse# bundle exec rails s -b 0.0.0.0:3000

Traceback (most recent call last):
	24: from bin/rails:4:in `<main>'
	23: from bin/rails:4:in `require'
	22: from /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/commands.rb:18:in `<top (required)>'
	21: from /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/command.rb:46:in `invoke'
	20: from /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/command/base.rb:65:in `perform'
	19: from /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/thor-0.19.4/lib/thor.rb:369:in `dispatch'
	18: from /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/thor-0.19.4/lib/thor/invocation.rb:126:in `invoke_command'
	17: from /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/thor-0.19.4/lib/thor/command.rb:27:in `run'
	16: from /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/commands/server/server_command.rb:142:in `perform'
	15: from /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/commands/server/server_command.rb:142:in `tap'
	14: from /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/commands/server/server_command.rb:145:in `block in perform'
	13: from /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/commands/server/server_command.rb:145:in `require'
	12: from /var/www/discourse/config/application.rb:38:in `<top (required)>'
	11: from /var/www/discourse/config/application.rb:39:in `<module:Discourse>'
	10: from /var/www/discourse/config/application.rb:220:in `<class:Application>'
	 9: from /var/www/discourse/lib/discourse.rb:148:in `activate_plugins!'
	 8: from /var/www/discourse/lib/discourse.rb:148:in `each'
	 7: from /var/www/discourse/lib/discourse.rb:151:in `block in activate_plugins!'
	 6: from /var/www/discourse/lib/plugin/instance.rb:457:in `activate!'
	 5: from /var/www/discourse/lib/plugin/instance.rb:457:in `instance_eval'
	 4: from /var/www/discourse/plugins/discourse-backups-to-dropbox/plugin.rb:7:in `activate!'
	 3: from /var/www/discourse/lib/plugin/instance.rb:527:in `gem'
	 2: from /var/www/discourse/lib/plugin_gem.rb:18:in `load'
	 1: from /usr/local/lib/ruby/site_ruby/2.5.0/rubygems/specification.rb:1437:in `activate'
/usr/local/lib/ruby/site_ruby/2.5.0/rubygems/specification.rb:2322:in `check_version_conflict': can't activate public_suffix-2.0.5, already activated public_suffix-3.0.2 (Gem::LoadError)