IE6 problems when using gzip_disable

[Maxim Dounin]

Hello!

On Thu, Jan 20, 2011 at 01:13:47PM -0500, dbro wrote:

> Hello-
> I am new to nginx, so this may be a silly question. I set up gzip with
> the recommended 'gzip_disable "MSIE [1-6]\."' parameter. But this

Just a side note: use "msie6" special mask instead.

> results in long delays and/or "IE cannot download" errors when used with
> keepalive and other gzip options. It only seems to affect js files, and
> if I rename the files to .txt extensions they have no problems. Does
> this mean that gzip doesn't need to be disabled for IE6 any more? Or am
> I doing something wrong somewhere else in my configuration?
> 
> Here is a description of the behavior and a debug log.
> When trying to download the static .js file for my site, it takes 30
> seconds to complete in IE6, compared to almost instant in
> chrome/firefox. This 30 second duration depends on the keepalive_timeout
> setting, which I have at 35. If I change that to 75, the download take
> 70 seconds to complete. If I change it to 0, the download completes
> right away. This affects files with the .js extension, but other files
> don't have this problem (.txt, .html). The debug log for 2 download
> attempts using IE6 (no service packs applied), first for the file with
> extension .txt and then for a file with extension .js:

Looking though logs suggests that there is nothing wrong at nginx 
side: it sent the whole file.

Probably (at least your installation of) IE6 has problems with 
downloading (big?) .js files over keepalive connections.  Gzip has 
mostly nothing to do with it as 1) it's disabled as expected, 2) 
one can't rely on content being gzipped all over the net anyway 
and 3) having problems with non-gzipped content doesn't mean there 
are no problems with gzipped one.

You may want to check the following:

1. If size or actual javascript content matters (i.e. if using 
smaller or simplier file makes any difference).

2. If removing gzip completely makes any difference.

3. If using another web server with keepalive support makes any 
difference.

4. If your IE6 installation is able to cache files (and time is 
set correctly).  Note that most of the problems with "IE can't 
download file" seems to be caused by "can't save to disk but need 
to" problem, see here:

http://support.microsoft.com/kb/812935

Maxim Dounin