Error: Object field starting or ending with [.]

[dC7]

Our service is logging via fluentd to elasticsearch and I've been starting recently to fix all errors seen in the Fluentd-Logs (so I'm not quite sure if I should ask here or the fluentd-team).

I'm nearly done, but I have no idea how to find and fix this one or what it acutally means:

"error"=>{"type"=>"mapper_parsing_exception", "reason"=>"failed to parse", "caused_by"=>{"type"=>"illegal_argument_exception", "reason"=>"object field starting or ending with a [.] makes object resolution ambiguous: [\v]"}}

I've looked through all used object fields but no one is having a "." in it.

It would be great if someone would know how to tackle this error

[rjernst (Ryan Ernst)]

Can you look at your elasticsearch log files to see the full stack trace? You should see another exception which contains the name of the field being parsed.

[dC7]

I looked at the log files and the entries just look like the following (shortened) one

Could not push log to Elasticsearch: 
{"took"=>182, "errors"=>true, "items"=>[
<a lot of working ones>,
{"index"=>
 {"_index"=>"some-service-log-2017.12.05", "_type"=>"some-service", "_id"=>"AWAmgPHDW8acwW_CgGC0", "status"=>400, "error"=>
  { "type"=>"mapper_parsing_exception", "reason"=>"failed to parse", "caused_by"=>
   {"type"=>"illegal_argument_exception", "reason"=>"object field starting or ending with a [.] makes object resolution ambiguous: [\v]"}
  }
 }
}
, <some more entries>
]}

I couldn't find any other exceptions (for this index) in there.

But after looking at the Index Patterns (in Kibana) again, I was able to find a strange looking field (mapped as object) ending with ".[a few spaces]"

I remapped the field to text and found out that this was the problem.

Thanks for your help.