突然，我的PuppetServer在重启后失败了。可以在日志中看到以下内容
2019-05-08 14:55:54,923 INFO [clojure-agent-send-pool-0] [p.s.j.jruby-puppet-internal] Creating JRuby instance with id 1.
2019-05-08 14:56:12,366 WARN [clojure-agent-send-pool-0] [puppet-server] Puppet Support for ruby version 1.9.3 is deprecated and will be removed in a future release. See https://docs.puppet.com/puppet/latest/system_requirements.html#ruby for a list of supported ruby versions.
(location: /opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet.rb:130:in `Puppet')
2019-05-08 14:56:12,431 WARN [clojure-agent-send-pool-0] [puppet-server] Puppet Setting 'pluginsync' is deprecated.
(location: /opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/defaults.rb:1819:in `handle')
2019-05-08 14:56:12,439 WARN [clojure-agent-send-pool-0] [puppet-server] Puppet Setting ignorecache is deprecated.
(location: /opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/settings.rb:1163:in `issue_deprecation_warning')
2019-05-08 14:56:12,460 ERROR [clojure-agent-send-pool-0] [p.t.internal] shutdown-on-error triggered because of exception!
java.lang.IllegalStateException: There was a problem adding a JRubyPuppet instance to the pool.
at puppetlabs.services.jruby.jruby_puppet_agents$eval16164$prime_pool_BANG___16169$fn__16173.invoke(jruby_puppet_agents.clj:60) ~[na:na]
at puppetlabs.services.jruby.jruby_puppet_agents$eval16164$prime_pool_BANG___16169.invoke(jruby_puppet_agents.clj:38) ~[na:na]
at puppetlabs.services.jruby.jruby_puppet_agents$eval16362$send_prime_pool_BANG___16367$fn__16368$fn__16370.invoke(jruby_puppet_agents.clj:181) ~[na:na]
at puppetlabs.trapperkeeper.internal$shutdown_on_error_STAR_.invoke(internal.clj:310) [na:na]
at puppetlabs.trapperkeeper.internal$shutdown_on_error_STAR_.invoke(internal.clj:295) [na:na]
at puppetlabs.trapperkeeper.internal$eval14032$shutdown_service__14037$fn$reify__14039$service_fnk__5289__auto___positional$reify__14044.shutdown_on_error(internal.clj:350) [na:na]
at puppetlabs.trapperkeeper.internal$eval13962$fn__13974$G__13954__13982.invoke(internal.clj:318) [na:na]
at puppetlabs.trapperkeeper.internal$eval13962$fn__13974$G__13953__13991.invoke(internal.clj:318) [na:na]
at clojure.core$partial$fn__4527.invoke(core.clj:2494) [puppet-server-release.jar:na]
at clojure.core$partial$fn__4527.invoke(core.clj:2493) [puppet-server-release.jar:na]
at puppetlabs.services.jruby.jruby_puppet_agents$eval16137$send_agent__16142$fn__16143$agent_fn__16144.invoke(jruby_puppet_agents.clj:32) [na:na]
at clojure.core$binding_conveyor_fn$fn__4444.invoke(core.clj:1919) [puppet-server-release.jar:na]
at clojure.lang.AFn.applyToHelper(AFn.java:154) [puppet-server-release.jar:na]
at clojure.lang.RestFn.applyTo(RestFn.java:132) [puppet-server-release.jar:na]
at clojure.lang.Agent$Action.doRun(Agent.java:114) [puppet-server-release.jar:na]
at clojure.lang.Agent$Action.run(Agent.java:163) [puppet-server-release.jar:na]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1152) [na:1.7.0_181]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:622) [na:1.7.0_181]
at java.lang.Thread.run(Thread.java:748) [na:1.7.0_181]
Caused by: org.jruby.embed.InvokeFailedException: (ArgumentError) Attempt to assign a value to unknown setting :always_cache_features
at org.jruby.embed.internal.EmbedRubyObjectAdapterImpl.call(EmbedRubyObjectAdapterImpl.java:317) ~[puppet-server-release.jar:na]
at org.jruby.embed.internal.EmbedRubyObjectAdapterImpl.callMethod(EmbedRubyObjectAdapterImpl.java:169) ~[puppet-server-release.jar:na]
at org.jruby.embed.ScriptingContainer.callMethod(ScriptingContainer.java:1509) ~[puppet-server-release.jar:na]
at com.puppetlabs.puppetserver.jruby.ScriptingContainer.callMethodWithArgArray(ScriptingContainer.java:33) ~[puppet-server-release.jar:na]
at puppetlabs.services.jruby.jruby_puppet_internal$eval15863$create_pool_instance_BANG___15868$fn__15869.invoke(jruby_puppet_internal.clj:228) ~[na:na]
at puppetlabs.services.jruby.jruby_puppet_internal$eval15863$create_pool_instance_BANG___15868.invoke(jruby_puppet_internal.clj:186) ~[na:na]
at puppetlabs.services.jruby.jruby_puppet_agents$eval16164$prime_pool_BANG___16169$fn__16173.invoke(jruby_puppet_agents.clj:53) ~[na:na]
... 18 common frames omitted
Caused by: org.jruby.exceptions.RaiseException: (ArgumentError) Attempt to assign a value to unknown setting :always_cache_features
PuppetServer版本如下：
$ rpm -q puppetserver puppetserver-2.3.1-1.el6.noarch
OS版本如下：
$$ cat / etc / redhat-release 红帽企业Linux服务器版本6.10（圣地亚哥）
请提出解决问题的方法。