Error message: Upgrading the 7.17.4 ES version to 8.5.2 ES cluster getting the below message. We have checked the deprecation messages and upgrade assistant and nothing was reported.
java.lang.IllegalStateException: cannot upgrade node because incompatible indices created with version [6.4.3] exist, while the minimum compatible index version is [7.0.0]. Upgrade your older indices by reindexing them in version [7.17.0] first.
AS per below article i am downgrading to 7.17.4 but not sure whether it will come up fine as index metadata might be changed or corrupted. Also master node not discovered exception we are getting while downgrading to 7.17 and _cat/indices is not working.
Thanks. Is there a way to check the index metadata version ? We have roll back to 7.17.4 and like to know to check for index metadata version of it is changed to 7.x or still in 6.x which needs reindexing ?