Using redis, get error like "Failed to send event to Redis"

Elastic Stack Logstash
1

Just installed logstash 2.3.4 -redis-elasticsearch 2.3.4

when test, error repeated in file logstash.log:
{:timestamp=>"2016-08-15T14:31:35.306000+0800", :message=>"Failed to send event to Redis", :event=>#<LogStash::Event:0x22ea422c @metadata={"path"=>"/var/log/messages1"}, @accessors=#<LogStash::Util::Accessors:0x6e5fb6c @store={"message"=>"abcdefg", "@version"=>"1", "@timestamp"=>"2016-08-15T06:31:34.885Z", "path"=>"/var/log/messages1", "host"=>"localhost.localdomain", "type"=>"syslog"}, @lut={"path"=>[{"message"=>"abcdefg", "@version"=>"1", "@timestamp"=>"2016-08-15T06:31:34.885Z", "path"=>"/var/log/messages1", "host"=>"localhost.localdomain", "type"=>"syslog"}, "path"], "host"=>[{"message"=>"abcdefg", "@version"=>"1", "@timestamp"=>"2016-08-15T06:31:34.885Z", "path"=>"/var/log/messages1", "host"=>"localhost.localdomain", "type"=>"syslog"}, "host"], "type"=>[{"message"=>"abcdefg", "@version"=>"1", "@timestamp"=>"2016-08-15T06:31:34.885Z", "path"=>"/var/log/messages1", "host"=>"localhost.localdomain", "type"=>"syslog"}, "type"], "message"=>[{"message"=>"abcdefg", "@version"=>"1", "@timestamp"=>"2016-08-15T06:31:34.885Z", "path"=>"/var/log/messages1", "host"=>"localhost.localdomain", "type"=>"syslog"}, "message"]}>, @data={"message"=>"abcdefg", "@version"=>"1", "@timestamp"=>"2016-08-15T06:31:34.885Z", "path"=>"/var/log/messages1", "host"=>"localhost.localdomain", "type"=>"syslog"}, @metadata_accessors=#<LogStash::Util::Accessors:0x54f11f97 @store={"path"=>"/var/log/messages1"}, @lut={"[path]"=>[{"path"=>"/var/log/messages1"}, "path"]}>, @cancelled=false>, :identity=>"default", :exception=>#<Redis::CommandError: ERR unknown command 'rpush'>, :backtrace=>["/opt/logstash/vendor/bundle/jruby/1.9/gems/redis-3.3.0/lib/redis/client.rb:121:in call'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/redis-3.3.0/lib/redis.rb:1070:inrpush'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/redis-3.3.0/lib/redis.rb:58:in synchronize'", "/opt/logstash/vendor/jruby/lib/ruby/1.9/monitor.rb:211:inmon_synchronize'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/redis-3.3.0/lib/redis.rb:58:in synchronize'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/redis-3.3.0/lib/redis.rb:1069:inrpush'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-output-redis-2.0.5/lib/logstash/outputs/redis.rb:246:in send_to_redis'", "org/jruby/RubyProc.java:281:incall'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-codec-json-2.1.4/lib/logstash/codecs/json.rb:42:in encode'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-output-redis-2.0.5/lib/logstash/outputs/redis.rb:152:inreceive'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.3.4-java/lib/logstash/outputs/base.rb:83:in multi_receive'", "org/jruby/RubyArray.java:1613:ineach'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.3.4-java/lib/logstash/outputs/base.rb:83:in multi_receive'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.3.4-java/lib/logstash/output_delegator.rb:130:inworker_multi_receive'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.3.4-java/lib/logstash/output_delegator.rb:114:in multi_receive'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.3.4-java/lib/logstash/pipeline.rb:301:inoutput_batch'", "org/jruby/RubyHash.java:1342:in each'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.3.4-java/lib/logstash/pipeline.rb:301:inoutput_batch'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.3.4-java/lib/logstash/pipeline.rb:232:in worker_loop'", "/opt/logstash/vendor/bundle/jruby/1.9/gems/logstash-core-2.3.4-java/lib/logstash/pipeline.rb:201:instart_workers'"], :level=>:warn}

Redis is running well.

2

Providing your config would be helpful.

3

[root@elastic conf.d]# pwd
/etc/logstash/conf.d
[root@elastic conf.d]# ls
shipper.conf
[root@elastic conf.d]# more shipper.conf
input {
file {
type => "syslog"
path => ["/var/log/messages","/var/log/messages1"]
exclude => ["*.gz"]
}
}

output {
stdout { }
redis {
host => "10.212.240.104"
data_type => "list"
key => "logstash"
}
}