new → closed
I've recreated your test case on my server and was able to receive a response from the server-side file being called by JSON without any issues. This was confirmed as including the undefined=undefined parameter at the end of the URL called.
Please remember that the file you're calling and expecting a JSON response from needs to both be in valid JSON format but also needs to be sending back valid content-type information in the header if you're using something like PHP.
eg. header('Content-type: application/json')
If you are able to provide the contents of your jsonpage.html file for further review please feel free to submit a new ticket.