# Date parse error

**URL:** <https://discuss.elastic.co/t/date-parse-error/84269>\
**Category:** Logstash\
**Created:** [May 2, 2017, 1:19pm UTC](https://discuss.elastic.co/t/date-parse-error/84269 "2017-05-02T13:19:34Z")\
**Posts on this page:** 1\
**Showing post:** 12

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**Author:** ![magnusbaeck](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/magnusbaeck/32/44943_2.png) [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)\
**Post date:** [May 3, 2017, 5:44am UTC](https://discuss.elastic.co/t/date-parse-error/84269/12 "2017-05-03T05:44:04Z")

</div>

> cannot convert instance of class org.jruby.RubyoObject to class java.lang.string

This indicates that the problem is that the field you're trying to parse already is a timestamp. I recently reported this in an issue ([Date filter fails to parse timestamps · Issue #95 · logstash-plugins/logstash-filter-date · GitHub](https://github.com/logstash-plugins/logstash-filter-date/issues/95)). As a workaround you can use the mutate filter's convert option to turn the field into a string.

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