We upgraded from 7.6.2 to 7.8.0 recently. The number of documents/shards have not change, but the controls visualization is now showing the error saying "Terms list may be incomplete because the request is taking too long". We had it set to kibana.autocompleteTerminateAfter : 10000000 . This used to fix that problem.
If I leave the setting in place as shown above, it causes another error that shows up in yellow saying "Data might be incomplete because your request timed out." If I remove the autocomplete setting completely, the yellow data error goes away.
I tried multiple times to increase it to fix this problem. The final attempt was increasing the autocomplete setting to kibana.autocompleteTerminateAfter : 2190000000 it then gives me an error "Unable to fetch Terms, error:"
I am not sure what else I can do. I have read through many issues related to this and have not seen anything like this.