Getting error index.max_inner_result_window during rolling upgrade of ES from 5.6.10 to 6.8.10 - elasticsearch

Question

I have 2 data nodes and 3 master nodes in an ES cluster. I was doing a rolling upgrade as ES suggested moving from 5.6.10 to 6.8.10.
As there should be zero downtime, I was testing that and getting one error.
I have upgraded the 1 data node and do basic search testing. It is working fine. When I have upgraded 2nd node search is breaking with the below Error.
java.lang.IllegalArgumentException: Top hits result window is too large, the top hits aggregator [top]'s from + size must be less than or equal to: [100] but was [999]. This limit can be set by changing the [index.max_inner_result_window] index level setting.
index.max_inner_result_window -- This property was introduced in the 6.X version, and the master node is still on 5.6.10. So what will be the solution with 0 downtimes?
Note: My indexing is stopped completely. My 2 data nodes are now on 6.8.10 and master nodes are on 5.6.
Thanks

Answer 1

1 - Change the parameter on current indexes:
curl -X PUT "http://localhost:9200/_all/_settings?pretty" -H 'Content-Type: application/json' -d'
{
"index.max_inner_result_window": "2147483647"
}
'
2 - Create a template to further indexes:
curl -X PUT "http://localhost:9200/_index_template/template_max_inner_result?pretty" -H 'Content-Type: application/json' -d'
{
"index_patterns": ["*"],
"template": {
"settings": {
"index":{
"max_inner_result_window": 2147483647
}
}
}
}
'