Oh, also — if it’s on Sync Gateway, you need to create the design documents using the Couchbase Server admin tool, because the views are actually run and managed by Couchbase Server itself.
So you’re talking to Couchbase Server itself, not Sync Gateway. I don’t know why this would fail. Does your Couchbase Server require authentication, and if so are you supplying the right credentials?
You’d be better off asking in one of the server topic areas, since this question isn’t directly related to Couchbase Mobile.