Gzipped response shown as raw data

Question

On the beta version of our new web app I've received this below messed up page from one of our test users.

The user uses FF on Mac. The site is build on asp.net (.NET 4.0), it uses AJAX and is running on Windows 2008 server using dynamic compression. The pages are in XHTML 1.0 Strict and the markup validates.

This user is the only one who has reported this error (we have tested for some time now, but might be the first user with FF on Mac). He is not able to systematically reproduce it, but it occurs from time to time.

I have no idea what is going on here, anyone seen this before?

Let me know if I should supply more info on our server setup or on the users setup.

Answer 1

I believe I have found a fix for this:

I did some testing and to my surprise experienced the same error myself on Firefox and Safari for windows.

Somewhere here on SO I found a suggestion to disable GZIP compression. I had both dynamic and static compression installed on the Windows Web Server 2008 R2 (iis7). First I uninstalled static which did not solve the problem. But after uninstalling both I have not seen the error. The error pages were (as far as I can tell) all with AJAX calls returning json involved.

All error pages started with something like this:

HTTP/1.1 200 OK Cache-Control: private Content-Type: text/html; charset=utf-8 Content-Encoding: gzip Vary: Accept-Encoding Server: Microsoft-IIS/7.5 X-AspNet-Version: 4.0.30319 X-Powered-By: ASP.NET Date: Tue, 29 Nov 2011 21:45:06 GMT Content-Length: 7534 ‹í½I–%&/mÊ{JõJ×àt¡€$Ø