I had to debug a weirdo IE download problem today. Clicking on a pdf, word or powerpoint link wouldn't do a thing. Right-clicking and saving the file gave a weird error message that IE couldn't "save the file to the cache". What?

I remembered having the same problem more than a year ago, but I couldn't remember the exact fix as I had a lot of small issues to solve at the same time on that older site.

In the end I found the problem . A combination of specific IE versions plus the use of https plus the presence of a Cache-control:no-cache header. You just can't make this sort of stuff up.

In my Plone site I solved it by tweaking my CacheFu cache config a bit:

• I added a separate header set with most of the cache headers off, especially the no-cache one.
• I attached that header set to my "Files" rule. Tadaah, problem solved.

Adding this to my own blog should help in remembering it next time :-)