Unexpected encoding line reader error when enabling multiline

I've been trying to get Filebeat (v1.1.1 on centos7) to apply a multiline filter before outputting a java log (utf-8 encoded) into redis. The java log looks like this:

2016-03-03 09:47:13,690 INFO Wall-e-main Robot - done processing, sleeping for 10 seconds
2016-03-03 09:47:19,101 INFO Wall-e-status ThreadedRobot - PoolSize: 18, ActiveCount: 0, QueueSize: 0
2016-03-03 09:47:23,696 INFO Wall-e-main ThreadedRobot - selected 0 articles for processing
2016-03-03 09:47:23,697 INFO Wall-e-main Robot - done processing, sleeping for 10 seconds
2016-03-03 09:47:29,039 INFO Roy-main Robot - refreshWorker articleIdKey null
2016-03-03 09:47:29,039 INFO Roy-main Robot - Return jedis connection to pool

There are also some java stack traces in there, which begin like this:

2016-03-03 09:46:52,562 ERROR Roy--Aggressive-worker-1 Dispatcher - RhinoException occurred while processing:

The filebeat config that i'm using is the following:

filebeat:
  prospectors:
    -
      paths:
        - /path/to/log
      input_type: log
      fields:
        logtype: robot
        environment: staging
      multiline:
        pattern: '^[[:digit:]]{4}-[[:digit:]]{2}-[[:digit:]]{2}' 
        negate: true
        what: after
          
output:
  redis:
    host: "1.2.3.4"
    port: 6379

With the multiline in place, I keep getting this error:

log.go:135: ERR Stop Harvesting. Unexpected encoding line reader error: unknown matcher type:

When I comment the multiline out, the file processes just fine. I already tried converting the file from utf-8 to ascii, which didn't do anything. The odd part is that the syslog, secure log and cron log process just fine with a multiline filter applied.

You are using what instead of match. See https://www.elastic.co/guide/en/beats/filebeat/current/configuration-filebeat-options.html#multiline This one is called differently then in LS.

Thank you! I completely missed that. It works now