Firefox & IE: Corrupted data when retrieved from cache - asp.net

Question

I have a request to the server which looks like this:
http://localhost/Combine.aspx/flag/file1.js,file2.js,file3.js
I have also tried this:
http://localhost/Combine.aspx/flag/value/file1.js/file2.js/file3.js
It simply combines the three files which it was given: this works fine.
Upon the first request from Firefox, the page displays correctly. When the page is refreshed again, the content looks like this:
��������`I�%&/m�{J�J��t��`$�����iG#)�*��eVe]f#�흼��{���{��;�N'
In that case, no request is made to the server, the file is only retrieved from the firefox cache, as far as I can tell.
If I force-refresh the page with Control-F5, the page looks normal again.
Here is the request and response (in firebug) with Control-F5 (works):
Response
Cache-Control public
Content-Type application/javascript; charset=utf-8
Content-Encoding gzip
Expires Sun, 26 Feb 2012 02:57:26 GMT
Last-Modified Fri, 07 Jan 2011 21:08:54 GMT
Etag CLYvZwbFmainWEMi8h-6x-zNEIQ1
Vary Accept-Encoding
Server Microsoft-IIS/7.5
Set-Cookie auth=longstring; path=/
X-AspNet-Version 2.0.50727
X-Powered-By ASP.NET
Date Thu, 03 Mar 2011 02:57:26 GMT
Content-Length 918
Request
Host localhost
User-Agent Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.14) Gecko/20110218 Firefox/3.6.14
Accept text/html,application/xhtml+xml,application/xml;q=0.9,*/;q=0.8
Accept-Language en-us,en;q=0.5
Accept-Encoding gzip,deflate
Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive 115
Connection keep-alive
Cookie auth=longstring
Pragma no-cache
Cache-Control no-cache
Here is the same with just F5 (doesn't work):
Response:
Cache-Control public
Content-Type application/javascript; charset=utf-8
Content-Encoding gzip
Expires Sun, 26 Feb 2012 02:57:26 GMT
Last-Modified Fri, 07 Jan 2011 21:08:54 GMT
Etag CLYvZwbFmainWEMi8h-6x-zNEIQ1
Vary Accept-Encoding
Server Microsoft-IIS/7.5
X-AspNet-Version 2.0.50727
X-Powered-By ASP.NET
Date Thu, 03 Mar 2011 03:01:31 GMT
Content-Length 1533
Request:
Host localhost
User-Agent Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.14) Gecko/20110218 Firefox/3.6.14
Accept text/html,application/xhtml+xml,application/xml;q=0.9,*/;q=0.8
Accept-Language en-us,en;q=0.5
Accept-Encoding gzip,deflate
Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive 115
Connection keep-alive
Cookie auth=longstring
The only thing that I can tell is different is the Content-Length (which is likely causing the corruption), but since it never hits the server, I have no control over it.
What could be causing this?
Edit:
This happens on IE8 as well, but instead of viewing a corrupt file, it downloads the corrupt file. No request is ever made to the server (set a breakpoint in visual studio).
As for chrome, when viewing the url directly, a request to the server is made every time, and it works every time. I believe, though, that if it were included in a tag, it would behave similar to Firefox.
Oh, and also:
If I turn off the Expires header (which is one of the flags in the URL), everything works fine.
Edit 2:
I was able to work around this by not sending both an Expires and ETag header, only one or the other. I have no clue why an ETag header would cause such corruption, though.

Answer 1

It is because of your IIS configuration. Adjust IIS as ASP 4.0 Classic, not Default Application Pool