Since Elasticsearch 5.2 to 5.4.0 (I haven't checked other versions, but these were installed on my server) I was able to use the following statement in my queries:
timestamp: [now-2d now]
It worked just fine. When I've upgraded to 5.5.0 it stopped working and now throws an exception (https://pastebin.com/6XxifrMW) saying I must put "TO" between "now-2d" and "now".
I've checked release notes for 5.5 and failed to find anything that could explain the change in behavior.
If it was an intentional change, I'll have no problems with changing my queries, but I just want to confirm that it wasn't a side effect of changes in something else.