# Upgrade assistant can not migrate system indeces during upgrade from 8.18.10 to 9 version

**URL:** <https://discuss.elastic.co/t/upgrade-assistant-can-not-migrate-system-indeces-during-upgrade-from-8-18-10-to-9-version/384973>\
**Category:** Elasticsearch\
**Created:** [February 9, 2026, 8:29am UTC](https://discuss.elastic.co/t/upgrade-assistant-can-not-migrate-system-indeces-during-upgrade-from-8-18-10-to-9-version/384973 "2026-02-09T08:29:49Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![GyurkanMehmed](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/gyurkanmehmed/32/146855_2.png) [@GyurkanMehmed](https://discuss.elastic.co/u/GyurkanMehmed)\
**Post date:** [February 9, 2026, 8:29am UTC](https://discuss.elastic.co/t/upgrade-assistant-can-not-migrate-system-indeces-during-upgrade-from-8-18-10-to-9-version/384973/1 "2026-02-09T08:29:49Z")

</div>

I have two clusters which i am trying to upgade to 9.1.0 from 8.18.10, but migrate system indices throws async\_search: illegal\_state\_exception, so I can not proceed with the upgrade. Both cluster were originally 7v and upgraded to 8. Any ideas what is causing this exact same error on two seperate clusters?

---

<div class="post-metadata">

**Author:** ![GyurkanMehmed](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/gyurkanmehmed/32/146855_2.png) [@GyurkanMehmed](https://discuss.elastic.co/u/GyurkanMehmed)\
**Post date:** [February 9, 2026, 9:20am UTC](https://discuss.elastic.co/t/upgrade-assistant-can-not-migrate-system-indeces-during-upgrade-from-8-18-10-to-9-version/384973/2 "2026-02-09T09:20:47Z")

</div>

So there were several issues, old closed .kibana-x indeces which prevented the migration and 2 templates which I deleted via the GUI .watches and .triggered\_watches. Migration assistant needs improvement, as it does not show the stack just illegal\_state\_exception, the output from GET \_migration/system\_features should be visible on the migration assistant page in the gui.