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mod_pagespeed's caching headers break image caching on IE8 #157

GoogleCodeExporter opened this issue Apr 6, 2015 · 1 comment


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What steps will reproduce the problem?
1. In IE8 Go to a page with an image with a short cache lifetime
2. Refresh the page twice (Control-F5) then hit return in the URL bar
3. Observe the Apache access.log

What is the expected output? What do you see instead?

Expected to see an access.log sequence like:

1. index.html       (from first Control-F5)
2. image.png
3. index.html       (from second Control-F5)
4. image.png.pagespeed.ce.HASH.png
5. index.html       (from RETURN in URL bar)
6. image.png.pagespeed.ce.HASH.png

We did not expect to see the final .png fetch.  This should have been cached by 
IE8 but was not.  In FF and IE9 this works fine.

This is true for all versions of mod_pagespeed through r311 and 0.12.*.

The problem is that mod_pagespeed was supplying a Vary header, which breaks 
caching of Images on IE8.  This problem can also be worked around by supplying 
an Etag, which will enable IE8 to validate its cache with an if-modified-since.

Original issue reported on by on 17 Dec 2010 at 11:39

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Fixed in

Original comment by on 18 Dec 2010 at 12:06

  • Changed state: Fixed

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