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:  but was . 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.