Getting No 'Access-Control-Allow-Origin' when sending large JSON via AJAX
By default browsers block json requests from other domains other than the page unless the json request has the Access-Control-Allow-Origin header, so you'll need to add that header to your json requests on that service or use the same domain for both.
More info here: https://developer.mozilla.org/en-US/docs/HTTP/Access_control_CORS
You can try setting the maxJsonLength to it's maximum value in the web.config file.
<system.web.extensions> <scripting> <webServices> <jsonSerialization maxJsonLength="2147483647"/> </webServices> </scripting></system.web.extensions>
I know this is an old post, but for anyone who still might be having this problem, I solved it by adding two settings to Web.config as described here: https://west-wind.com/webconnection/docs/_4lp0zgm9d.htm
<system.webServer> <security> <requestFiltering> <requestLimits maxAllowedContentLength="2147483647"></requestLimits> </requestFiltering> </security> <!--snip--></system.webServer>and
<system.web> <httpRuntime maxRequestLength="2147483647" /> <!--snip--></system.web>