Actually i have installed 5.6.3 elasticsearch and created some indexes not i want to install new version of elastic search 7.4.2 so in that case i followed below steps
1.Take backup by creating snap shot for 5.6.3 version.
2.Now install 6.6.2 and restore these snapshots which i have created in 5.6.3.
3.Then again uninstall 6.6.2 and install 7.4.2 but while restoring these snapshot then it is showing the below result
The index [[cielasticsearch_1_report_1_2-2020.03.28-16.29-1/o3PhNL-pQkKus0ITj0BFHw]] was created with version [5.6.3] but the minimum compatible version is [6.0.0-beta1]. It should be re-indexed in Elasticsearch 6.x before upgrading to 7.4.2
Could you please help me out how to do this .....