Access is denied to XMLHTTPRequest

hello,

I am writing a handler to send json string to my server.  I am then trying to append a file with the string which will be picked up later and uploaded to a database.  I am running into issues getting this error:  SCRIPT7002: XMLHttpRequest: Network Error 0x80070005, Access is denied

I have CORS enabled with green responses for Cross Origin and CORS preflight.  I am at a loss as to what else needs to be done. 

I can post any of the code necessary.

Thanks