We were using ES 2.4 in our production. We are now testing 5.x and planning on migration.
However, we found that our SDK is using [cluster_endpoint]/?timeout=1000 to check whether the cluster is existed or not. But when we use the same SDK on 5.x, the HTTP respond is 400 instead of 200.
I believe there are some breaking changes on 5.x right?
Please help to advice. Thanks