# Upgrade elasticsearch from 6.8 to 7.8 date format

**URL:** <https://discuss.elastic.co/t/upgrade-elasticsearch-from-6-8-to-7-8-date-format/240072>\
**Category:** Elasticsearch\
**Created:** [July 7, 2020, 1:18am UTC](https://discuss.elastic.co/t/upgrade-elasticsearch-from-6-8-to-7-8-date-format/240072 "2020-07-07T01:18:25Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![krishm](https://avatars.discourse-cdn.com/v4/letter/k/53a042/32.png) [@krishm](https://discuss.elastic.co/u/krishm)\
**Post date:** [July 7, 2020, 1:18am UTC](https://discuss.elastic.co/t/upgrade-elasticsearch-from-6-8-to-7-8-date-format/240072/1 "2020-07-07T01:18:25Z")

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Hello There,

I am working on elasticsearch upgrade from 6.8 to 7.x. i have a date field using format below and i understand that i need to change the mapping to "uuuu-MM-dd HH:mm:ss" before upgrading to elasticsearch 7.8  
"type" : "date",  
"format" : "yyyy-MM-dd HH:mm:ss"

i have 6 months worth of data in my cluster and i cant wait 6 months to upgrade to 7.x. Do I have to reindex all data with new new mapping enabled? what will happen if i don't reindex data and use new format for the date field going forward. do my searches break?

Thanks for checking.

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [August 4, 2020, 1:18am UTC](https://discuss.elastic.co/t/upgrade-elasticsearch-from-6-8-to-7-8-date-format/240072/2 "2020-08-04T01:18:25Z")

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