Search Indices and Locales
Some search indices work in all locales; some search indices do not. Supported search indices in a locale often changes over time. For example, a search index, such as Automotive, that works in the US locale can be added to the JP locale.
Support for search indices varies by locale often because of the data that Amazon does or does not have. For example, the search index, Grocery, is currently supported in the US locale only because grocers in other countries have not yet teamed up with Amazon to provide grocery items for sale. As the data grows over time, more and more search indices will be supported in all locales.
When you specify a search index in a request, make sure it is supported in the locale of interest. For a list of the search indices supported in different locales, see Search Index Support by Locale.