Hi Plamen,
I only placed the handler's code behind file in Handler.ashx and did a test run of your sample project and the result is the same. Both query string variables contains NULL value when I try to upload larger than 2048KB, but smaller files are fine. I've tried Chrome 25 & IE10 and both produced the same result. I'm running Windows 8, .net 4.5.
Any idea?
Thanks.