# What makes ES not support rollbacks?

**URL:** <https://discuss.elastic.co/t/what-makes-es-not-support-rollbacks/245392>\
**Category:** Elasticsearch\
**Created:** [August 18, 2020, 10:26am UTC](https://discuss.elastic.co/t/what-makes-es-not-support-rollbacks/245392 "2020-08-18T10:26:45Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![jbaker](https://avatars.discourse-cdn.com/v4/letter/j/59ef9b/32.png) [@jbaker](https://discuss.elastic.co/u/jbaker)\
**Post date:** [August 18, 2020, 10:26am UTC](https://discuss.elastic.co/t/what-makes-es-not-support-rollbacks/245392/1 "2020-08-18T10:26:45Z")

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A number of documents are clear that it's possible to upgrade from one ES version to the next, but not downgrade. I'm wondering what the causes of this are? I assume there's a necessary forwards compatibility guarantee between the files that are kept on disk which is not currently met.  
Is this purely because of upgrades to the underlying Lucene files or are there additional issues here? I'd assume that the translog files could potentially be a problem, but I'm not sure how frequently the format of those gets changed (I would guess infrequently compared to Lucene). Likewise, cluster state seems like it could be problematic.

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**Author:** ![Christian\_Dahlqvist](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/christian_dahlqvist/32/4617_2.png) [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)\
**Post date:** [August 18, 2020, 11:04am UTC](https://discuss.elastic.co/t/what-makes-es-not-support-rollbacks/245392/2 "2020-08-18T11:04:56Z")

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I believe this was recently answered [in this thread](https://discuss.elastic.co/t/reason-for-version-downgrade-not-supported/245200).

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**Author:** ![jbaker](https://avatars.discourse-cdn.com/v4/letter/j/59ef9b/32.png) [@jbaker](https://discuss.elastic.co/u/jbaker)\
**Post date:** [August 18, 2020, 11:28am UTC](https://discuss.elastic.co/t/what-makes-es-not-support-rollbacks/245392/3 "2020-08-18T11:28:29Z")

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Brilliant. Guess lightning sometimes strikes twice. Thanks!

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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:** [September 15, 2020, 11:28am UTC](https://discuss.elastic.co/t/what-makes-es-not-support-rollbacks/245392/4 "2020-09-15T11:28:36Z")

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