There was an issue with the upgrade script that prevented the logstash config files from being updated properly. This will be fixed asap on our end so a new download later today should fix it. In the meantime though you can run:
{:timestamp=>"2017-11-14T11:59:05.156000-0500", :message=>"Pipeline aborted due to error", :exception=>"LogStash::ConfigurationError", :error=>"The setting `host` in plugin `elasticsearch` is obsolete and is no longer available. Please use the 'hosts' setting instead. You can specify multiple entries separated by comma in 'host:port' format. If you have any questions about this, you are invited to visit https://discuss.elastic.co/c/logstash and ask.", :backtrace=>["/usr/local/nagioslogserver/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.4.1-java/lib/logstash/config/mixin.rb:88:in `config_init'", "org/jruby/RubyHash.java:1342:in `each'", "/usr/local/nagioslogserver/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.4.1-java/lib/logstash/config/mixin.rb:72:in `config_init'", "/usr/local/nagioslogserver/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.4.1-java/lib/logstash/outputs/base.rb:79:in `initialize'", "/usr/local/nagioslogserver/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.4.1-java/lib/logstash/output_delegator.rb:74:in `register'", "/usr/local/nagioslogserver/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.4.1-java/lib/logstash/pipeline.rb:181:in `start_workers'", "org/jruby/RubyArray.java:1613:in `each'", "/usr/local/nagioslogserver/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.4.1-java/lib/logstash/pipeline.rb:181:in `start_workers'", "/usr/local/nagioslogserver/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.4.1-java/lib/logstash/pipeline.rb:136:in `run'", "/usr/local/nagioslogserver/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.4.1-java/lib/logstash/agent.rb:491:in `start_pipeline'"], :level=>:error}
{:timestamp=>"2017-11-14T11:59:08.165000-0500", :message=>"stopping pipeline", :id=>"main"}