MapperParsingException no handler for type string on django_ct

[turukawa]

Hi, hoping this is the right place to raise this.

I'm running Ubuntu 18.04 with ElasticSearch 6.4.3, Django 2.1.3 and Django Rest Framework. I'm using EdgeNgramField to index street addresses. This is a new build after running on successfully on Ubuntu 16, and lower versions of everything else.

When I run rebuild_index, I get the below error in the logs. I remember seeing this a year or so ago, and I remember fixing it by installing elasticstack, but now I'm at a bit of a loss as to what it means, or what I need to do about it.

Help would be much appreciated:

org.elasticsearch.index.mapper.MapperParsingException: No handler for type [string] declared on field [django_ct]
        at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseProperties(ObjectMapper.java:274) ~[elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.index.mapper.ObjectMapper$TypeParser.parseObjectOrDocumentTypeProperties(ObjectMapper.java:199) ~[elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.index.mapper.RootObjectMapper$TypeParser.parse(RootObjectMapper.java:131) ~[elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.index.mapper.DocumentMapperParser.parse(DocumentMapperParser.java:112) ~[elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.index.mapper.DocumentMapperParser.parse(DocumentMapperParser.java:92) ~[elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.index.mapper.MapperService.parse(MapperService.java:626) ~[elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.cluster.metadata.MetaDataMappingService$PutMappingExecutor.applyRequest(MetaDataMappingService.java:263) ~[elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.cluster.metadata.MetaDataMappingService$PutMappingExecutor.execute(MetaDataMappingService.java:229) ~[elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.cluster.service.MasterService.executeTasks(MasterService.java:639) ~[elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.cluster.service.MasterService.calculateTaskOutputs(MasterService.java:268) ~[elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.cluster.service.MasterService.runTasks(MasterService.java:198) [elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.cluster.service.MasterService$Batcher.run(MasterService.java:133) [elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.cluster.service.TaskBatcher.runIfNotProcessed(TaskBatcher.java:150) [elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.cluster.service.TaskBatcher$BatchedTask.run(TaskBatcher.java:188) [elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingRunnable.run(ThreadContext.java:624) [elasticsearch-6.4.3.jar:6.4.3]
        at org.elasticsearch.common.util.concurrent.PrioritizedEsThreadPoolExecutor$TieBreakingPrioritizedRunnable.runAndClean(PrioritizedEsThreadPoolExecutor.java:244) [elasticsearch-$
        at org.elasticsearch.common.util.concurrent.PrioritizedEsThreadPoolExecutor$TieBreakingPrioritizedRunnable.run(PrioritizedEsThreadPoolExecutor.java:207) [elasticsearch-6.4.3.ja$
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_191]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_191]
        at java.lang.Thread.run(Thread.java:748) [?:1.8.0_191]

[bennylope]

I'd love to know here for other people if you figure this out, but I've got nothing on this - sorry!