Invalid format: [ISO8601] when indexing logs in ElasticSearch

elasticsearch.log

[2015-01-09 15:52:59,854][DEBUG][action.admin.indices.create] [perfgen04 1] [logaggr-2015.01.09] failed to create
org.elasticsearch.index.mapper.MapperParsingException: mapping [test]
        at org.elasticsearch.cluster.metadata.MetaDataCreateIndexService$2.execute(MetaDataCreateIndexService.java:386)
        at org.elasticsearch.cluster.service.InternalClusterService$UpdateTask.run(InternalClusterService.java:328)
        at org.elasticsearch.common.util.concurrent.PrioritizedEsThreadPoolExecutor$TieBreakingPrioritizedRunnable.run(PrioritizedEsThreadPoolExecutor.java:153)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.IllegalArgumentException: Invalid format: [ISO8601]: Illegal pattern component: I
        at org.elasticsearch.common.joda.Joda.forPattern(Joda.java:160)
        at org.elasticsearch.common.joda.Joda.forPattern(Joda.java:37)
        at org.elasticsearch.index.mapper.core.TypeParsers.parseDateTimeFormatter(TypeParsers.java:295)
        at org.elasticsearch.index.mapper.core.DateFieldMapper$TypeParser.parse(DateFieldMapper.java:155)
        at org.elasticsearch.index.mapper.object.ObjectMapper$TypeParser.parseProperties(ObjectMapper.java:289)
        at org.elasticsearch.index.mapper.object.ObjectMapper$TypeParser.parseObjectOrDocumentTypeProperties(ObjectMapper.java:217)
        at org.elasticsearch.index.mapper.object.RootObjectMapper$TypeParser.parse(RootObjectMapper.java:136)
        at org.elasticsearch.index.mapper.DocumentMapperParser.parse(DocumentMapperParser.java:209)
        at org.elasticsearch.index.mapper.DocumentMapperParser.parseCompressed(DocumentMapperParser.java:190)
        at org.elasticsearch.index.mapper.MapperService.parse(MapperService.java:440)
        at org.elasticsearch.index.mapper.MapperService.merge(MapperService.java:313)
        at org.elasticsearch.cluster.metadata.MetaDataCreateIndexService$2.execute(MetaDataCreateIndexService.java:383)
        ... 5 more
Caused by: java.lang.IllegalArgumentException: Illegal pattern component: I
        at org.elasticsearch.common.joda.time.format.DateTimeFormat.parsePatternTo(DateTimeFormat.java:570)
        at org.elasticsearch.common.joda.time.format.DateTimeFormat.createFormatterForPattern(DateTimeFormat.java:693)
        at org.elasticsearch.common.joda.time.format.DateTimeFormat.forPattern(DateTimeFormat.java:181)
        at org.elasticsearch.common.joda.Joda.forPattern(Joda.java:158)
        ... 16 more
[2015-01-09 15:53:00,953][DEBUG][action.admin.indices.create] [perfgen04 1] [logaggr-2015.01.09] failed to create
org.elasticsearch.index.mapper.MapperParsingException: mapping [test]
        at org.elasticsearch.cluster.metadata.MetaDataCreateIndexService$2.execute(MetaDataCreateIndexService.java:386)
        at org.elasticsearch.cluster.service.InternalClusterService$UpdateTask.run(InternalClusterService.java:328)
        at org.elasticsearch.common.util.concurrent.PrioritizedEsThreadPoolExecutor$TieBreakingPrioritizedRunnable.run(PrioritizedEsThreadPoolExecutor.java:153)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.IllegalArgumentException: Invalid format: [ISO8601]: Illegal pattern component: I
        at org.elasticsearch.common.joda.Joda.forPattern(Joda.java:160)
        at org.elasticsearch.common.joda.Joda.forPattern(Joda.java:37)
        at org.elasticsearch.index.mapper.core.TypeParsers.parseDateTimeFormatter(TypeParsers.java:295)
        at org.elasticsearch.index.mapper.core.DateFieldMapper$TypeParser.parse(DateFieldMapper.java:155)
        at org.elasticsearch.index.mapper.object.ObjectMapper$TypeParser.parseProperties(ObjectMapper.java:289)
        at org.elasticsearch.index.mapper.object.ObjectMapper$TypeParser.parseObjectOrDocumentTypeProperties(ObjectMapper.java:217)
        at org.elasticsearch.index.mapper.object.RootObjectMapper$TypeParser.parse(RootObjectMapper.java:136)
        at org.elasticsearch.index.mapper.DocumentMapperParser.parse(DocumentMapperParser.java:209)
        at org.elasticsearch.index.mapper.DocumentMapperParser.parseCompressed(DocumentMapperParser.java:190)
        at org.elasticsearch.index.mapper.MapperService.parse(MapperService.java:440)
        at org.elasticsearch.index.mapper.MapperService.merge(MapperService.java:313)
        at org.elasticsearch.cluster.metadata.MetaDataCreateIndexService$2.execute(MetaDataCreateIndexService.java:383)
        ... 5 more
Caused by: java.lang.IllegalArgumentException: Illegal pattern component: I
        at org.elasticsearch.common.joda.time.format.DateTimeFormat.parsePatternTo(DateTimeFormat.java:570)
        at org.elasticsearch.common.joda.time.format.DateTimeFormat.createFormatterForPattern(DateTimeFormat.java:693)
        at org.elasticsearch.common.joda.time.format.DateTimeFormat.forPattern(DateTimeFormat.java:181)
        at org.elasticsearch.common.joda.Joda.forPattern(Joda.java:158)
        ... 16 more

logaggr-test.json

{
    "template": "logaggr-*",
    "mappings": {
        "test": {
            "dynamic": "strict",
            "date_detection": false,
            "properties": {
                "timestamp": { "type": "date", "format": "YYYY-MM-dd HH:mm:ss,SSSZ"},
                "_timestamp": { "enabled": true },
                "logts": { "type": "string" },
                "level": { "type": "string" },
                "thread": { "type": "string" },
                "classname": { "type": "string" },
                "details": { "type": "string"}
            }
        }
    }
}

logstash.conf

input {
    file {
        path => "/work/elk/logaggr-test/LogAggr_Test.log"
        start_position => "beginning"
    }
}

filter {
    grok {
        match => [ "message", "%{DATA:logts}%{SPACE}\[%{LOGLEVEL:level}%{SPACE}]%{SPACE}\[%{DATA:thread}]%{SPACE}\[%{DATA:classname}]%{SPACE}%{GREEDYDATA:details}" ]
    }
    #date {
    #    match => [ "logts", "yyyy-MM-dd HH:mm:ss,SSS" ]
    #}
}

output {
    # Uncomment next line to debug
    #stdout { codec => rubydebug }
    # Always include elasticsearch
    elasticsearch {
        cluster => "perfgen04"
        host => "10.X.X.X"
        port => 9201
        index => "logaggr-%{+YYYY.MM.dd}"
        protocol => "http"
        template => "logaggr-test.json"
        template_name => "test"
    }
}