IIS Dynamic Compression Failing

Question

I'm trying to get Dynamic Compression on IIS 8.5 to work (particularly with JSON). I'm using Windows Server 2012, IIS 8.5 and a very simple ASP.NET MVC site returning an ActionResult in the form of JSON. Firstly I have done all the usual steps, enabling Dynamic Compression in IIS at the server and site level, edited my applicationHost.config with the correct MIME types, frequency etc.

I have enabled FailedRequestTrace logging, and what is strange is that my request is reporting a successful compression, however Chrome/Fiddlr disagree:

And the response in Trace logging contains the header "Content-Encoding: gzip":

But the response in Chrome/IE/Fiddlr does not contain that header nor is the response compressed, it would appear that something else is interfering! Please help!

Answer 1

If the server is serving the response zipped (use WireShark to determine this) but you are seeing the response deflated in the browser it's likely to be your antivirus unzipping before the content gets to your browser

WireShark