Can't close ElasticSearch index on AWS?

I've created a new AWS ElasticSearch domain, for testing. I use ES on a different host right now, and I'm looking to move to AWS.

One thing I need to do is set the mapping (analyzers) on my instance. In order to do this, I need to "close" the index, or else ES will just raise an exception.

Whenever I try to close the index, though, I get an exception from AWS:

Your request: '/_all/_close' is not allowed by CloudSearch.

The AWS ES documentation specifically says to do this in some cases:

 curl -XPOST 'http://ift.tt/1hDceep'

I haven't found any documentation that says why I wouldn't be able to close my indices on AWS ES, nor have I found anyone else who has this problem.

It's also a bit strange that I've got an ElasticSearch domain, but it's giving me a CloudSearch error message, since I thought those were different services, though I suppose one is implemented in terms of the other.

thanks!