# JSON Filter fails on valid key names
**URL:** https://discuss.elastic.co/t/json-filter-fails-on-valid-key-names/232244
**Category:** Logstash
**Created:** [May 12, 2020, 2:32pm UTC](https://discuss.elastic.co/t/json-filter-fails-on-valid-key-names/232244 "2020-05-12T14:32:21Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@davehatma](https://discuss.elastic.co/u/davehatma)
#### Post date: [May 12, 2020, 2:32pm UTC](https://discuss.elastic.co/t/json-filter-fails-on-valid-key-names/232244/1 "2020-05-12T14:32:21Z")
I have some Kafka messages that have key names that contain reserved Logstash characters -- specifically '[" and "]". Additionally the json document also has arrays.
My Logstash pipeline is generating:
[WARN][logstash.filters.json][unilog] Exception caught in json filter {:exception=\>"Invalid FieldReference: `custom_news[0][code]`"
I would attempt to change the key names by treating the entire document as a string first and then using the JSON Filter, but with the "[" and "]" characters ALSO designating arrays in the document that is quite cumbersome and seems should be unnecessary as the key names are indeed valid for json documents.
Any help/insight as to how I can resolve this without a ton of coding would be appreciated.
Thanks.
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### Author:  [@Badger](https://discuss.elastic.co/u/Badger)
#### Post date: [May 12, 2020, 2:58pm UTC](https://discuss.elastic.co/t/json-filter-fails-on-valid-key-names/232244/2 "2020-05-12T14:58:47Z")
This is an [open issue](https://github.com/logstash-plugins/logstash-filter-json/issues/38).
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [June 9, 2020, 2:58pm UTC](https://discuss.elastic.co/t/json-filter-fails-on-valid-key-names/232244/3 "2020-06-09T14:58:52Z")
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