Layar supports backwards compatibility so that layers created using older versions of API can still run in newer clients. The layar server will remove fields that are not defined/supported from the response, which may lead to unintended behavior on older clients. Therefore, it is very important that developers choose the right minimum API version for their layers. Regarding getPOIs API v6.0, geo-location layers using API v6.0 are supported on Layar client v5.0 and older. However, in the future, layers written in newer API might not be supported in older clients.

We have seen some compatibility issues and we are improving the error messages on the API test page to make it easier for everybody to debug their layer.

Here are some general best practices that might help reduce this kind of errors:

1. Please double check your JSON response against the API specification, especially the type of the parameters. A valid JSON response on JSON validator tool (such as jsonlint) does not necessarily mean that it is valid against layar API.

2. Please remove optional parameters which use default values. This will also make the transaction much faster.

If you still experience issue after trying the two suggestions above, please do not hesitate to post them on forums or create a ticket in devsupport.